Content 1 GENERAL REMARKS 4 1.1 APPLICATIONS 4 1.2 FUNCTION 4 1.2.1 CENTRING 4 1.2.2 EXPANDING PROBE 4 1.2.3 FLOATING CONTACTING 5 1.3 ADVANTAGES 5 2 CONSTRUCTION 7 2.1 OD MEASURING SLEEVE 7 2.1.1 BASIC DESIGNS OF OD MEASURING SLEEVES 7 2.1.1.1 Standard h 7 2.1.1.2 Through bores 7 2.1.1.3 Blind bores 7 2.1.1.4 Deviating h 8 2.1.2 ENGRAVING OF THE OD MEASURING SLEEVES 8 2.1.3 MATERIAL OF THE OD MEASURING SLEEVES 8 2.1.3.1 Hard-chromed measuring sleeve 8 2.1.3.2 Stainless steel design 8 2.1.3.3 Dynamant coating 8 2.1.3.4 Delrin coating 9 2.1.4 UNDERSIZE OF THE OD SLEEVE 9 2.1.4.1 Reduced undersize 9 2.1.4.2 Enlarged undersize 9 2.1.5 MEASURING CONTACTS 9 2.1.5.1 Material of the measuring contacts 9 2.1.5.1.1 Hardchromed measuring contacts 10 2.1.5.1.2 Ruby measuring contacts 10 2.1.5.1.3 Ceramic measuring contacts 10 2.1.5.1.4 Diamond measuring contacts 10 2.1.5.1.5 Delrin measuring contacts 10 2.1.5.1.6 Coated measuring contacts 10 2.1.5.2 Measuring travel of the measuring contacts 10 2.1.5.2.1 Reduced measuring travel 11 2.1.5.2.2 Enlarged measuring travel 11 2.1.5.3 Form and size of the measuring contacts 11 2.1.5.3.1 Wedge-shaped measuring contacts 11 2.1.5.3.2 Enlarged measuring contacts 11 2.1.5.4 Measuring pressure 11 2.1.6 INSERTION CHAMFER 12 2.1.6.1 Insertion chamfer for automatic measurement 12 2.1.6.2 Second insertion chamfer 12 2.1.6.3 No insertion chamfer 12 2.1.7 COVER AT THE BOTTOM OF THE SLEEVE 12 2.2 OD HOLDER 12 2.2.1 OD HOLDER 50 13 2.2.2 OD HOLDER 105 13 2.2.3 OD HOLDER 235 13 2.2.4 OD HOLDER 70 WITH RETRACTION 13 2.2.5 OD HOLDER F 13 Page 1
Content 2.2.6 OD HOLDER P 13 2.2.7 TURNABLE HOLDER 13 2.3 INDICATING UNITS 14 3 TECHNICAL DATA 15 3.1 COMPONENTS 15 3.1.1 MEASURING NEEDLE 15 3.1.2 EXPANDING PROBE 15 3.1.3 MEASURING SLEEVE 15 3.2 ACCURACY 15 3.3 CONSTRUCTION GROUPS 15 3.3.1 DIAMETER 2,5 6 MM 15 3.3.2 DIAMETER 6,1 20 MM 16 3.3.3 DIAMETER 20,1 60 MM 16 3.3.4 DIAMETER 60,1 130 MM 16 3.3.5 OPEN DESIGN 16 3.3.5.1 Diameter < 20 mm 16 3.3.5.2 Diameter 20-30 mm 16 3.3.5.3 Diameter > 30 mm 16 3.3.6 THREE-POINT DESIGN 16 3.3.7 MEASURING OF LARGE DIAMETERS 17 3.3.7.1 Cross sleeve ODK 17 3.3.7.2 Cross sleeves with runners ODKK 18 3.3.7.3 Adjustable measuring sleeves 18 3.3.7.3.1 Adjustable cross sleeve ODV 18 3.3.7.3.2 Adjustable cross sleeve with runners ODVD 19 4 ACCESSORIES 20 4.1 MEASURING DEPTH EXTENSION 20 4.2 ANGLE PIECE 20 4.3 DEPTH STOP 20 4.3.1 SET COLLAR 21 4.3.2 CLAMPING UNIT 21 4.3.3 THREE-POINT DEPTH STOP 21 4.3.4 BRIDGE DEPTH STOP 21 4.3.5 ANGLE DEPTH STOP 22 4.4 MEASURING STAND 22 4.5 FLOATING HOLDER 22 4.6 BLOWING DEVICE 22 4.7 SETTING RINGS DIN 2250 C 22 4.8 SETTING MASTER ESU 23 4.9 WOODEN BOX 23 5 SELECTION CRITERIA 24 5.1 ACCURACY REQUIREMENTS 24 5.2 GEOMETRY OF THE BORE 25 5.2.1 TYPE OF BORE 25 5.2.1.1 Through bore 25 5.2.1.2 Deep hole bore 25 Page 2
Content 5.2.1.3 Blind hole bore 25 5.2.1.4 Short bore 25 5.2.1.5 Series bores 25 5.2.1.6 Bore with a tight tolerance 26 5.2.1.7 Bore with a wide tolerance 26 5.2.2 FORM OF THE BORE 26 5.2.2.1 Cylindricity and roundness deviations 26 5.2.2.2 Polygonal bore 26 5.3 MATERIAL OF THE BORE 26 5.3.1 STEEL 26 5.3.2 ALUMINIUM AND OTHER NON-FERROUS METALS 26 5.3.3 GREY CAST IRON 27 5.3.4 SYNTHETIC 27 5.4 SURFACE OF THE BORE 27 5.4.1 HIGH SURFACE ROUGHNESS 27 5.4.2 POLISHED SURFACE 27 5.5 SPECIAL INTERNAL PROFILES 28 5.5.1 PLANE PARALLEL DISTANCE 28 5.5.2 INTERNAL TAPER 28 5.5.3 STEPPED BORE 28 5.5.4 BORE WITH INTERRUPTED CIRCUMFERENCE 28 5.5.5 BORE WITH A CENTRAL HUB 29 5.5.6 PROFILE WITH SEVERAL WEDGES 29 5.5.7 GROOVES 29 5.6 ENVIRONMENT CONDITIONS 30 5.7 AUTOMATIC MEASURING 30 6 DIRECTIONS FOR USE 31 6.1 CALIBRATING POSSIBILITIES 31 6.2 MEASURING ERRORS 31 6.3 CARE OF THE INSTRUMENT 32 6.4 REPAIR 32 6.5 INSPECTION OF THE INSTRUMENT 32 Page 3
General 1 GENERAL REMARKS The OD plug gauge is a mechanical two-point contact comparator measuring instrument suited for manual or automatic measurement. Each measuring instrument is specially tailored to suit a specific bore diameter and the corresponding tolerance. The OD plug gauge serves for the reliable, fast and accurate measurement of bores with a diameter from 2,5 to 500 mm, as well as their deviations in form, without searching for the reversal point on the indicating unit. For the indication of the measuring value, precision indicators, mechanical or electronic dial gauges or electronic probes can be used. 10 20 30 40 50 mytast 10 20 30 40 50 Precision Indicator mytast 1.1 Applications The OD plug gauge is a robust and easy to use comparator measuring instrument, which is conceived for the series control of bores. The OD plug gauge is especially suited for the use in the production and can also be used in the incoming or final inspection. The OD plug gauge is the ideal replacement for usual plug gauges, whenever the statement acceptable / not acceptable is not satisfying. As a matter of fact, the deviations from the tolerance reference are precisely indicated in the µm scale. The OD plug gauge offers a special advantage: a very high measuring instrument capability can be achieved with this instrument. Therefore, this measuring instrument requires no special skills and is also suitable for unskilled users. It is possible to use the OD plug gauge either manually, with a measuring stand, or as a part of a fully automatic measuring station. Holder 105 OD Measuring sleeve 1.2 Function The bore measuring instrument OD consists principally of two parts: the measuring sleeve for the centring the expanding probe as measuring element DH DB OD plug gauge: alignment in the bore 1.2.1 Centring The surface line of the OD sleeve centres and aligns the measuring instrument automatically in the bore. The height of the OD sleeve ensures a large contact surface with the bore and prevents therefore any tilting of the measuring instrument in the bore. 1.2.2 Expanding probe The measuring or expanding probe located inside the plug gauge is split open by the spring power of the indicating unit (for example dial gauge) and by its own tension. Through the wedge-shaped measuring needle, the radial movement of the expanding probe OD plug gauge: centring in the bore Page 4
General corresponds exactly to the movement of the measuring needle. The precisely manufactured wedge of the measuring needle guarantees an excellent linearity. 1.2.3 Floating contacting The OD plug gauge includes two radially movable contact pins offset by 180, which can move independently. Therefore, the measuring contacts come into contact with the bore wall, independently of the position of the sleeve in the bore. The travel of the two measuring contacts is transferred to the indicating unit through the measuring needle and shows the deviation from the reference or setting dimension. Deviation of the measuring travel Measuring needl Measuring contacts 1.3 Advantages Highest precision The precision of a comparator gauge is shown clearly with the repeatability. For the OD plug gauge, this is max. 0,5 to 1 µm (for standard design up to diameter 130 mm), given an appropriate surface roughness. s Measuring travel s only with right contact Easy handling The user only has to enter the measuring instrument in the bore and the indicating unit shows the measuring result immediately. The position of the measuring axis has no influence on the result. High measuring certainty Due to an optimal adaptation of the OD sleeve to a specific measuring situation, the measuring instrument is automatically centred and guided in the bore. Therefore, the systematic measuring errors by the operator are negligible. Thus, the measurements can also be carried out by unskilled users in a secure and reliable way. Fast measuring process A stationary measuring value is obtained immediately when entering the bore to be measured. This enables a large number of measurements within the shortest time. s s/2 s/2 Measuring travel s symetric Measuring travel s only with left contact High flexibility All the OD measuring sleeves and the corresponding holders have generally a thread connection M 11 x 0,75. Therefore, it is possible to choose any combination required; a quick adjustment to any measuring task is guaranteed. Accessories, like for example an angle piece or measur- Floating contacting Page 5
General ing depth extensions, can be assembled without any adapter. Moreover, all kinds of standard indicating units with clamping shaft 8 H7 or 3/8 can be used with the OD holder. Furthermore, SCHWENK product range includes a large number of special plug gauges, which design is based on the proved OD principle. No tilting The unique insertion chamfer at the bottom of the measuring sleeve prevents any tilting when entering the measuring instrument in the bore. ødh x < D ød High service life / robustness The robust OD measuring sleeves, made of hardened and grinded tool steel, are suitable for the use in the production. As an option, hard chromed measuring sleeves are available, which offer more protection against wear and corrosion. The measuring contacts are as a standard fitted with tungsten carbide balls. The wedge-shaped measuring needle is generally made of tungsten carbide. Through the simple and modular construction, the OD system enables a very easy maintenance. E: Height of the insertion chamfer (see chapter 2.1.6) OD measuring sleeve insertion chamfer Easy setting As dimensional reference for the setting of the OD plug gauge, setting rings are often used in practice. This operation is very fast, since searching for the reversal point is not necessary for the setting either. Cross sleeve with runners From 130 mm, SCHWENK offers the so-called cross sleeve or cross sleeve with runners. In opposition to the conventional full round OD sleeve, the cross sleeve (with runners) presents advantages regarding the weight and the handling when measuring large diameters. The user can look into the bore during the measuring operation. Cross sleeve ODKK with runners Cross sleeve ODK Page 6
Construction 2 CONSTRUCTION The OD system consists of the following components: indicating unit (dial gauge, precision indicator, etc...) 10 20 30 40 50 10 20 30 40 50 Precision Indicator Dial gauge Electronic probe holder with thread connection M 11 x 0,75 - suitable for all OD measuring sleeves mytast exchangeable measuring sleeves made of hardened and grinded tool steel, hard chromed on request, adjusted to each bore diameter with tolerance; with an integrated expanding probe and wedge-shaped needle Options: Depth stop, measuring depth extension, etc... Setting reference: setting ring, master piece, setting device, reference unit RV, etc... (see also chapter 6.1). OD Holder 105 2.1 OD measuring sleeve 2.1.1 Basic designs of OD measuring sleeves The difference between the three basic designs which are mainly used in practice results from the type of bore to be measured. The distance between the measuring axis and the lower edge of the measuring sleeve is decisive therein. The appropriate term of SCHWENK for this is the so-called front distance h. The manufacturing tolerance of the front distance h is generally 0,2 mm. The manufacturing tolerance of the front distance h is generally 0,2 mm. The three situations are: OD plug gauge: construction OD Measuring sleeve 2.1.1.1 Standard h This design enables the most universal measurements. Depending on the (6 < d < 130 mm), h is between 2,5 and 3,5 mm. 2.1.1.2 Through bores With this OD-type, bore diameters can already be measured from the very beginning of the bore, because the centring and aligning of the measuring sleeve is already ensured. For < 6 mm, h = 6 mm. h = standard OD measuring sleeve: design with standard h 2.1.1.3 Blind bores With blind bores, the user wants to measure the diameter as close as possible to the bottom of the bore. Depending on the diameter, h is 1,0 or 1,2 mm. Page 7
Construction For < 20 mm, a h starting at 0,5 mm is possible. Disadvantage: The measuring sleeve or the measuring contacts are sharp-edged and complicate the entering of the measuring sleeve in the bore. 2.1.1.4 Deviating h A front distance which deviates from the standard is available on request, in order to measure the diameter at a certain distance from the bottom of the bore. 2.1.2 Engraving of the OD measuring sleeves Unless otherwise requested, the dimension ordered is engraved on the OD sleeve, for example 30 H7. A different engraving is possible. However, especially on OD sleeves for small bores, space for engraving is limited. The engraving of the measuring sleeves is normally to be found on the following position: h = 10 OD measuring sleeve: design h = 10 For all designs > 60 mm with a cover, the dimension is engraved on the cover. For all designs without a cover in the range 6 60 mm, the shaft is engraved. For the range 2,5-6 mm, the key surface SW 10 is engraved. Special engraving on request. 2.1.3 Material of the OD measuring sleeves The OD sleeves are as a standard made of hardened and grinded tool steel with a hardness of about 62 HRC. Depending on the use and on the environment conditions, the following variations are possible: 2.1.3.1 Hard-chromed measuring sleeve A hard-chrome coating is applied to the outside of the OD sleeve. This extends the service life of the OD sleeve in a rough environment. Advantages: hardness about 1000 HV, protection against wear and corrosion. h = 1,2 OD measuring sleeve: design for blind bores h = 1,2 Key surface SW 10 Shaft 2.1.3.2 Stainless steel design The OD sleeve can be made of stainless steel. Hardness: about 60 HRC. Advantage: protection against corrosion. Cover Position of the engraving 2.1.3.3 Dynamant coating Page 8
Construction This special coating offers an excellent protection against wear, the hardness is about 3000 HV. Recommended as an alternative to TIN coating, because a higher hardness and a lower coefficient of friction are reached. 2.1.3.4 Delrin coating Delrin is a thermoplast with a good chemical resistance and high limit temperatures of use (up to 150 C). It is used especially for measuring in scratch sensible work pieces. In this case, Delrin is coated on the sleeve surface (and also on the measuring contacts). Advantages: no scratching on sensible bore walls, protection against corrosion. U Ø DH Ø DB 2.1.4 Undersize of the OD sleeves The undersize of the OD sleeve is the difference between the real bore diameter and the outside diameter of the measuring sleeve. The undersize of the measuring sleeve has to be chosen in such a way that, on the one hand, only a negligible tilting and centring error arises and, on the other hand, that the entering of the plug gauge in the bore is not made more difficult. 2.1.4.1 Reduced undersize If the bore has a very tight tolerance, a reduced undersize can increase the measuring accuracy further, since the tilting and centring error is minimised. Under extreme circumstances, the OD sleeve can additionally have the function of a usual plug gauge. 2.1.4.2 Enlarged undersize If the bores present deviations in form (out-ofroundness), an enlarged undersize, in comparison with the standard, might be necessary (see the table herewith). Remark: Under such circumstances, it might be also necessary to enlarge the standard measuring travel of 0,2 mm. The measuring uncertainty increases! U = DB DH U: Undersize DB: Bore DH: Measuring sleeve range [mm] Nominal undersize ± 0,005 [mm] 2,5 20 0,02 20 40 0,025 40 130 0,03 130 200 0,04 200 300 0,05 300 700 0,07 Table nominal undersize 2.1.5 Measuring contacts 2.1.5.1 Material of the measuring contacts The measuring contacts are as a standard made of wear-resisting tungsten carbide. This design has proved its efficiency, especially when measuring steel work pieces. Under special circumstances (for instance due to the bore material and the wear conditions), it is necessary to choose a different material than tungsten carbide. Page 9
Construction 2.1.5.1.1 Hardchromed measuring contacts When measuring work pieces made of aluminium or other non-ferrous metals, respectively alloys of those, there is the danger that a built-up edge can appear on the tungsten carbide measuring contacts (cold soldering), especially if there is a dry friction between the work piece and the measuring contacts. In that case, hard-chromed measuring contacts offer a good alternative. The hardness of the coating is about 1000 HV. 2.1.5.1.2 Ruby measuring contacts Measuring contacts made of ruby are suitable if the environment is very abrasive, or if the work piece is made of aluminium or non-ferrous metals. The hardness is about 2000 HV. The ruby measuring contacts are not available for the blind bore version. range [mm] Standard measuring contacts, carbide Contact radius [mm] 3 3,4 0,6 3,4 4 0,7 4 4,8 0,85 4,8 5,6 1,0 5,6 6 1,1 6,1 20 1,2 20 60 1,5 60 500 2,5 Table: standard measuring contacts radii 2.1.5.1.3 Ceramic measuring contacts Ceramic measuring contacts can be used as an alternative to the ruby design. They have the advantage of being less brittle than ruby. 2.1.5.1.4 Diamond measuring contacts Measuring contacts made of diamond present similar characteristics as ruby measuring contacts, but with a higher hardness. However, they are not recommended because of the high costs. 2.1.5.1.5 Delrin measuring contacts Delrin measuring contacts are recommended if the bore to be measured presents a very smooth and scratch sensible surface, for example after polishing. Delrin is however less wear-resisting, so that it is necessary to recalibrate more often. 2.1.5.1.6 Coated measuring contacts To improve the abrasion behaviour, the measuring contacts of the open design (see chapter 3.3.5) are fitted with a special TIN-coating. Measuring contacts OD-sleeve Ø 3 6 R 1,2 2.1.5.2 Measuring travel of the measuring contacts The measuring travel of the OD sleeves 6 130 mm is generally 0,2 mm, for Ø < 6 mm 0,15 mm. However, the measuring travel can be reduced or enlarged, depending on the measuring situation. Generally speaking, the smaller the measuring travel, the better the linearity of the measuring instrument or the maximal deviation of the measuring instrument over the whole measuring range. Measuring contacts OD-sleeve Ø 6 20 Page 10
Construction 2.1.5.2.1 Reduced measuring travel For bores with a tight tolerance, the standard measuring travel of the measuring sleeve can be reduced, for example to ease the entering of the sleeve in the bore. 2.1.5.2.2 Enlarged measuring travel The standard measuring travel of 0,2 mm is not sufficient if the tolerance of the bore to be measured is large, or if the bore has to be measured before finishing. The following maximal measuring travels are possible: 0,2 mm for 2,5 6 mm 0,6 mm for 6,1 20 mm 0,8 mm for 20,1 500 mm R 1,5 Measuring contacts OD-sleeve Ø 20 60 R 2,5 Measuring contacts OD-sleeve Ø 60 500 2.1.5.3 Form and size of the measuring contacts The measuring contacts are classified in relation with the different construction groups of the OD measuring sleeves (see chapter 3.3). The form and the size are selected in order to offer an optimal measuring process, as well as a maximal service life. 2.1.5.3.1 Wedge-shaped measuring contacts Wedge-shaped measuring contacts are used to measure core diameters of threads, or diameters which can only be measured over a very short length. Measuring contacts open design 2.1.5.3.2 Enlarged measuring contacts Such measuring contacts are recommended for the measurement of bores with a high surface roughness and under extreme wear conditions, for example in grey cast iron. The enlarged contact radius (R = 5 mm) filters the measuring values. Furthermore, the service life of the measuring contacts is increased. Measuring contacts with enlarged radii are used in the sleeves in open design. 2.1.5.4 Measuring pressure The measuring pressure of a standard OD sleeve is 0,5 1 N, without considering the holder or the indicating unit used. This measuring pressure can be increased on request. In order to obtain the global measuring pressure of the OD system, the measuring pressures of both the OD holder and the indicating unit have to be added to the measuring pressure of the OD sleeve. s s1 s2 Measuring travel of OD sleeve: The measuring travel is composed of: s = s 1 + s 2 Measuring contact wedge shaped Page 11
Construction 2.1.6 Insertion chamfer The insertion chamfer of the measuring sleeve serves for the easy entering of the measuring instrument in the bore (no tilting). The height of the insertion chamfer depends on the diameter of the sleeve (see diagram). R~e ød e 5 ax45 b E c The following special designs are available: OD sleeve insertion chamfer 2.1.6.1 Insertion chamfer for automatic measurement Due to the smaller at the bottom of the OD-sleeve, inaccuracies of the positioning are evened out. A floating holder (see accessories) can also be used additionally, in order to enable a radial movement, so that the measuring sleeve finds its way into the bore. [mm] E;c 16 14 12 10 c = E+a+b [mm E [mm] 2.1.6.2 Second insertion chamfer When measuring discontinuous bores, the re-exiting of the sleeve is difficult. To solve this problem, an OD sleeve with a second insertion chamfer can be supplied. 2.1.6.3 No insertion chamfer Due to the height of the insertion chamfer, no alignment of the sleeve is possible in short bores. Therefore, in this case, it can be useful to do without the insertion chamfer. Please let us know if you wish no insertion chamfer when you order, this is made free of charge. 8 6 4 2 20 40 60 80 100 120 140 160 180 200 e [mm] ød [mm] Diagram: height E of the insertion chamfer in relation to the diameter 1 0.5 2.1.7 Cover at the bottom of the sleeve OD sleeves in the standard design from 60 mm have a glued cover. This cover prevents the entering of dirt inside the sleeve. A cover is available on request, already from 8 mm. 2.2 OD holder The OD holder represents the connection between the measuring sleeve and the indicating unit. The dial gauge holder serves for clamping of the indicating unit (dial gauge, precision indicator, electronic probe). It can be adapted to the shaft diameter 8 H7 or 3/8. In principle, all holders are provided with a thread connection M 11 x 0,75. A tube made of Invar steel enables the holders 105 and 235 to reduce considerably the influence of the hand heat of the user on the measuring result, as well as to offer a protection against corrosion. OD sleeve with double insertion chamfer 30.00 OD sleeve with automatic insertion chamfer Page 12
Construction 2.2.1 OD holder 50 The holder 50 is a low-cost version, which has no connecting rod. The indicating unit is contacting directly the measuring needle. Ø 8 H7 2.2.2 OD holder 105 The holder 105 is suitable for larger measuring depths and offers a better handling than the holder 50. The strengthened version with tube 18 is recommended for heavier measuring sleeves, approximately from diameter 80 mm. 2.2.3 OD holder 235 The holder 235 is longer than the holder 105. It is suitable therefore for larger measuring depths. For the holder in strengthened version with tube 18, the same applies as for the holder 105. The measuring depth of the OD holder 235 is approx. 150 mm. 45 OD holder 50 M11 x 0,75 Ø 8 H7 Ø 19 2.2.4 OD Holder 70 with retraction With the help of this OD holder, the measuring pressure of the indicating unit can be taken off when entering the bore with the OD measuring sleeve. This is especially useful with sleeves which have a small front distance ( h 1 mm) and for very scratch sensible surfaces. Moreover, the measuring contacts are protected against wear. 106 60 ~ ø 19 2.2.5 OD holder F The OD holder F was conceived for the use of electronic length measuring probes as measuring system. This holder enables a more secure reception of the electronic length measuring probes, in comparison to the other OD holders and offers the best protection against concussions and splash water. This holder also offers a protection against buckling and a strain relief probe cable. Furthermore, it enables the fine setting, so that the adjusting is made very fast. 9 OD holder 105 M11 x 0,75 ø 11,9 2.2.6 OD holder P The OD holder P with a pistol-like handle offers advantages concerning the handling of the plug gauge, provided that the bore axis is horizontal. 2.2.7 Turnable holder This holder enables a 360 rotation of the measuring Page 13
Construction sleeve, while the indicating unit keeps its initial position. The turnable holder offers advantages when checking the roundness of bores. 2.3 Indicating units For the indication of the measuring value, precision indicators, mechanical or electronic dial gauges or electronic probes can be used. The clamping shaft of the OD holder is 8 H7 as a standard, on request 3/8. The OD holder type F is recommended when using electronic length measuring probes. The following should be taken into consideration when choosing an indicating unit: the measuring pressure of the indicating unit has an effect on the service life and on the precision of the measuring instrument. An indicating unit with a very low measuring pressure might be recommended for measuring thin-walled or dimensionally instable work pieces. ø30 ~221 ø32 ø14 SW13 M11x0,75 OD Holder F ø 8H7 ø 20 ø 14 69 ø 11,9 10 OD holder with retraction Page 14
Technical data 3 TECHNICAL DATA All dimensions mentioned below without any specification are in mm. The technical data and dimensions are based on the current technical status at the time of the printing of this documentation. Changes are reserved. Measuring needle Expanding probe Contact pin 3.1 Components The OD measuring sleeves consist of three main components: Expanding probe OD-measuring sleeve 3.1.1 Measuring needle The wedge-shaped needle is made of tungsten carbide. It deviates the radial movement of the contact pins into an axial movement to the indicating unit. 3.1.2 Expanding probe The expanding probe is the storage place of the contact pins and generates the measuring pressure. Ø in [mm] 3-40 40-130 130-200 200-300 300-500 Reapeatability 0,5 1 2 2 3 µm Accuracy of the OD-measuring sleeves 2 2 2 3 4 max. deviation Hysteresis 1 1,5 2 3 5 3.1.3 Measuring sleeve The measuring sleeve enables the centring and the alignment of the measuring instrument in the bore. The components probe and wedge-shaped needle are integrated in the measuring sleeve. 5 14 M 11 x 0,75 Ø 11,9 The material used is tool steel. The hardness is about 62 HRC. 1,5 27 1,5 24 3.2 Accuracy The following values correspond to the standard design, measured in a setting ring in the measuring room and under repeatable conditions (see table on the right): Ø 4-6 Ø 3-4 OD-measuring sleeve range 3 6 mm 3.3 Construction groups The main difference between the single construction groups of OD measuring sleeves is the connection between the measuring contacts and the expanding probe. M11 x 0,75 9 3.3.1 Diameter 2,5 6 mm 60 In the range from 2,5 to 6 mm, tungsten carbide balls with a size adapted to the diameter to be measured are fixed directly on the expanding probe. 39 2.5 15 Starting from 2 mm, OD sleeves in special design are available. ø D OD-measuring sleeve range 6 20 mm Page 15
Technical data 3.3.2 Diameter 6,1 20 mm In the range from 6 to 20 mm, the measuring contact points are tungsten carbide pins, so that the contact between the measuring needle and the probe is also very wear-resisting. 3.3.3 Diameter 20,1 60 mm Hexagon pins with an internal thread are screwed on hardened set screws. A tungsten carbide ball with 3 mm is pressed in each hexagon pin. 3,5 20 60 3.3.4 Diameter 60,1 130 mm For larger diameters, the measuring contacts (tungsten carbide balls with 5 mm) are additionally guided in the measuring sleeve, which guarantees a high stability, also when measuring large diameters. Ø D OD measuring sleeve range 20 40 mm 3.3.5 Open design The so-called open design is available in the range from 6 to 130 mm. Characteristics of this design: 60 enlarged measuring radii higher measuring pressure 49 3,5 28 no easily soiled corners, easy cleaning The construction of the open design is based on the standard series. However, there are essential differences between the open design and the standard series: Ø D OD measuring sleeve range 40 60 mm 3.3.5.1 Diameter < 20 mm Tungsten carbide balls with a maximum large diameter are soldered on the probe. 3.3.5.2 Diameter 20-30 mm This design is based on the construction group 20-60. Enlarged measuring contacts with a bevel radius R 3 are used, instead of balls with diameter R 1,5. 9 M11 x 0,75 ø 11,9 SW 10 49 3.3.5.3 Diameter > 30 mm The measuring contacts with R = 5 are fixed on a plate spring. This guarantees a higher measuring pressure, as well as a very robust instrument, also under unfavourable environment conditions. Ø D 3,5 33 3.3.6 Three-point design Measuring sleeves with three measuring contacts instead of two are necessary if a bore is polygonshaped and if this deviation in form has to be meas- OD measuring sleeve range 60 130 mm Page 16
Technical data ured. Furthermore, a three-point design can be necessary to measure discontinuous bores with an odd pitch. In this design, one half of the probe has two measuring contacts, while the other one only has one. Through a special grinding of the measuring needle, the linearity or maximal deviation achieved with this design is within 1 % of the measuring travel. This is enough, given the small measuring travel (max. 0,2 mm). 3.3.7 Measuring of large diameters The measuring of large diameters represents a special challenge. The measuring instrument has to be as rigid as possible, while its weight should be minimised, in order to guarantee an easy handling. The solution is to reduce the cylindrical form of the measuring sleeve to a cross. This cross serves for the measuring and for the centring. Two different designs are available to measure, on the one hand short bores and centring shoulders and through bores on the other hand. 120.00 60.00 OD-measuring sleeve three point design 3.3.7.1 Cross sleeve ODK The cross sleeve ODK is used to measure diameters > 130 mm. This cross sleeve comprises a measuring arm and a centring arm, which are linked through a hub. The cross sleeve ODK is useful to measure short bores and centring shoulders, or whenever the bottom of the bore or a depth stop can be used for the alignment. Several designs with different front distances are available (see table below). 27 Ø D OD-measuring sleeve open design 49 Ø in [mm] 130-300 300-500 Ø D > 130 mm Ø r h Standard h blind hole h blind hole 12 6 3 1,5 18 9 3 1,5 Ø r Concerning the design for blind holes h = 3/1,5, the dimension d has to be known with the order in addition to the bore diameter D, in order to determine the range to be offset when manufacturing the cross sleeve. Cross sleeve ODK Ø > 130 mm The contact pins are guided in accordance with the Page 17
Technical data proven principle of the measuring sleeves 60 130 mm. OD sleeves for bores > 500 mm can also be made. (Registration of design no. 94 04 093) h h = 6/9 ø D ø 12/18 3.3.7.2 Cross sleeves with runners ODKK The cross sleeves with runners are available from diameter > 130 mm, like the usual cross sleeves. The runners enable the alignment without a depth stop or the positioning at the bottom of the bore. The measuring principle is the same as for measuring sleeves from 45 mm. The following designs corresponding to different applications are available: Cross sleeve ODK for blind bores ø d H Ø in [mm] 130-300 300-500 h Tube Ø r Height H h Standard h Blind hole h Blind hole 12 66 18 10 1,5 18 86 25 - - Ø r OD sleeves for bores > 500 mm can also be made. (Registration of design no. 94 04 093) 3.3.7.3 Adjustable measuring sleeves A plug gauge is conceived only for a certain bore dimension. Generally, only high quantities of the same work piece justify the conception of a special measuring instrument. The series production of work pieces with large bores is generally limited. Their dimensions vary, or similar designs inside a family of parts are to be measured. The adjustable plug gauge, which offers the same advantages as a usual plug gauge, was conceived in order to meet this requirement. Like for the cross sleeve series, the measuring sleeve of the adjustable plug gauge is reduced to one measuring axis and one centring axis. Two electronic length measuring probes are used as measuring element. The smallest diameter to be measured with the series ODV is 100 mm, the adjustable range is up to 170 mm. Cross sleeve ODKK for Ø > 130 mm 3.3.7.3.1 Adjustable cross sleeve ODV The adjustable cross sleeve ODV serves for the same applications as the cross sleeve ODK, when a depth Page 18
Technical data stop can be used or when the measuring instrument can be positioned at the bottom of the bore. 3.3.7.3.2 Adjustable cross sleeve with runners ODVD The adjustable cross sleeve with runners ODVD has a second centring unit, which guarantees the alignment of the measuring instrument without a depth stop or a positioning at the bottom of the bore. Plug in extension tubes, up to 10 meters all in all, are available to measure large measuring depths. These extension tubes are linked with the ODVD through a cardan joint. This cardan guarantees that the weight of the extension tubes does not stress the measuring instrument excessively. Adjustable cross sleeve ODV 250 Page 19
Accessories 4 ACCESSORIES 4.1 Measuring depth extension If the measuring depth of the holder 105 or 235 is not enough to reach the bore to be measured, measuring depth extensions MTV can be screwed between the measuring sleeve and the holder. M11x0.75 SW10 Ø 4 L M3,5x0,35 The measuring depth extensions MTV are made of Invar steel, which is insensitive to heat. All designs with tube 12 and 18 have a connecting thread M 11. The measuring depth extensions MTV are available in different lengths and tube : L Ø 12/18 7-11 M3,5x0,35 4 mm for measuring sleeves from 4 mm 6 mm for measuring sleeves from 6 mm M11x0,75 Measuring depth extension Ø 4, Ø 12 8 mm for measuring sleeves from 8 mm 12 mm for measuring sleeves from 12 mm 18 mm for measuring depths > 1000 mm and measuring sleeves with > 80 mm, or together with the holder 18 mm. 9 38,5 M11 x 0,75 9 For OD measuring sleeves with Ø < 12 mm it has to be known with the order, that a MTV is needed. Later an adaptation of the OD measuring sleeve is not possible. The connecting rod of all measuring depth extensions MTV with 12 or 18 mm is fitted with a spring. This guarantees a sufficient measuring pressure, also when measuring over head. 11 OD angle piece ø12 9 32 4.2 Angle piece It is possible to reach awkwardly positioned bores with an angle piece. The angle piece enables a 90 deviation of the measuring travel and can be connected on the one hand to the holder and on the other hand to the measuring sleeve, through the thread M 11. The admissible accuracy deviations of the measuring sleeve are enlarged as follows when using the angle piece: Repeatability: + 1 µm Maximal deviation: + 1 µm Hysteresis: + 2 µm 24 50 Clamping unit for depth stop 20 4.3 Depth stop It is possible to measure always with a certain and Page 20
Accessories repeatable measuring depth, when using a depth stop. b Another advantage of the depth stop, especially when measuring short bores, is that the tilting error is reduced, which results in a higher accuracy. The measuring depth to be reached with each depth stop can be set by the user to a certain extent. D ø DA A depth stop, integrated in the measuring sleeve in the form of a shoulder, enables the most precise measurement with an exactly determined measuring depth. The measuring depth has to be mentioned in the purchase order. Set collar 4.3.1 Set collar The set collar is fixed on the outside diameter of the OD sleeve. It is ideal for measuring bores with a short measuring depth (height of the set collar - height of the measuring sleeve), for sleeves up to 60 mm. ø24 ø11,9 The set collar is not recommended when measuring larger diameters, because of the weight. 15 20 4.3.2 Clamping unit The clamping unit can also be used directly as a depth stop for measuring sleeves 45 mm. The measuring depth MT has to be higher than the length H of the sleeve (see 4.3.4). Clamping units with 108 mm and 160 mm are further available. ø5 35 M4 4.3.3 Three-point depth stop This depth stop offers a precisely defined three-point support. The measuring depth can be set by the user, so that the bore can be measured from the very beginning. The max. depth to be reached depends on the holder or MTV used. It is recommended to use this depth stop instead of a set collar for measuring sleeve diameters from 60 mm. øb Three-point depth stop Nom.-ø + 10 41 20 / 35 4.3.4 Bridge depth stop When measuring with a bridge depth stop, the minimal measuring depth is defined by the height of the measuring sleeve. The maximal depth to be reached depends on the length of the holder or MTV used. A clamping unit is generally necessary to use a bridge depth stop. 2,2 Ø 4 12,5 ø 8 4 Bridge depth stop, for use only with the clamping unit Page 21
Accessories 4.3.5 Angle depth stop A simple angle depth stop is available for measuring with the cross sleeve ODK. This angle depth stop is clamped on the measuring or centring axis. The requested measuring depth has to be mentioned in the purchase order. 4.4 Measuring stand Through the measuring stand, it is possible to change easily and at low costs the manual measuring instrument OD plug gauge into a stationary measuring device. With certain work processes, it can be better to bring the work piece to the measuring instrument and not conversely. This is especially true for small and light work pieces. If not specified otherwise the stand is supplied with a clamping Ø 12 mm. 4.5 Floating holder If the OD plug gauge is used in a measuring station with automatic supply of the work piece, then either the work piece or the measuring instrument should be flexibly positioned, in order to compensate the inaccuracies of the positioning. This is possible with the floating holder, which offers a radial degree of freedom of 0,5 mm. In that case, a measuring sleeve with a 30 insertion chamfer should be used, which eases the insertion of the plug gauge into the bore to be measured. Ø D Ø + 10 OD-measuring sleeve with bridge depth stop MT Angle depth stop for cross sleeve ODK ø12 measuring depth 4.6 Blowing device The bore to be measured has to be free of remainders like swarf or coolant and lubricant residues. A blowing device integrated in the measuring sleeve is useful to clean the parts of the bore, on which the measuring contacts are to be positioned. A blowing device is possible for Ø > 20 mm on enquiry. 135 102 Ø 25 Ø 110 150 4.7 Setting rings DIN 2250 C The OD plug gauge has to be calibrated regularily, since it is a comparator measuring instrument. Setting rings DIN 2250 are especially useful to calibrate the OD plug gauges. They present the same measuring situation as in the bore and guarantee a high precision. 5,5 Measuring stand Page 22
Accessories The standard diameter tolerance of the setting ring is JS 3. The nominal dimension can be selected every 1 µm. 0,5 8 Setting rings with the form B are available on request. They are higher than setting rings with the form C and are useful to minimise further the possible tilting errors. 26 12 Ø 10 / Ø 11,9 Furthermore, setting rings with a higher accuracy are available. 11H7 4.8 Setting master ESU The setting master ESU, which was developed to calibrate the internal precision measuring instrument SUBITO, can also be used for the OD plug gauges. Setting jaws are not necessary for the calibration of the latter. Concerning the full round design up to 130 mm, the OD measuring sleeve is positioned on the gauge block combination. For calibration, the minimum value has to be searched by turning the measuring sleeve to-andfro. 41 35 72,5 Floating holder for OD plug gauge Prisms are available to ease the alignment of the cross sleeves during the setting. They enable a simple and quick setting operation. The setting master ESU is especially useful with larger diameters, since setting rings for larger diameters are expensive and difficult to handle. 4.9 Wooden box Four different sizes of wooden box are available. The wooden box is useful to store securely a plug gauge, a holder, a dial gauge and eventually a setting ring. OD-plug gauge with floating holder 10 10 20 20 30 30 40 40 50 50 mytast Setting device ESU for ODK/ODKK Page 23
Selection 5 SELECTION CRITERIA Due to the numerous designs and accessories, it is not easy to choose the optimal combination to solve each measuring problem. The following summary of selection criteria should help the user to select quickly and reliably from the comprehensive OD-system the measuring instrument suited for his specific measuring situation. 80 52 5.1 Accuracy requirements The OD plug gauge can generally be used when tolerances lower than 0,2 mm have to be measured. The maximal measuring accuracy to be reached in practice depends on the following criteria: correct handling clean work piece and instrument contact surfaces Ø D 2,5 OD-measuring sleeve in special length to reduce the tilting error the roughness of the contacted surface corresponds with the diameter tolerance required the measuring axis is vertically and aligned to the bore axis the temperature of the environment, measuring instrument, work piece and reference is 20 C the measuring instrument is calibrated before and after each measuring series a short holder is used (L = 50 mm) the measuring instrument is used, cleaned, stored and transported appropriately Please read the actual values for the accuracies in the table, chapter 3.2. The following measures can increase the measuring accuracy and certainty: the measuring sleeve undersize U is reduced in relation to the lower tolerance limit of the bore in order to align the measuring axis radially, the sleeve is positioned on the face side or a depth stop (bridge, set collar, etc...) is used alternatively Plug gauge OD with depth stop for alignment and / or reproducible measuring depth a sleeve with enlarged sleeve length H is used, in order to reduce the tilting error a blind sleeve is used with larger bore depth, which can reduce considerably the tilting error measuring contacts with an enlarged radius, in order to reduce the effect of the surface roughness Page 24
Selection 5.2 Geometry of the bore The geometry of a bore includes the diameter, as well as the deviations in form, the length and possibly profilings or the interruptions. 5.2.1 Type of bore 5.2.1.1 Through bore The OD plug gauge can be used without any restriction in all usual through bores, which length L equals at least the sleeve length H. A front distance h = 10 mm is used preferably. Then it is possible to measure from the beginning to the end of the bore. 1,2 OD-measuring sleeve for short blind holes without insertion chamfer 5.2.1.2 Deep hole bore With a very long bore or a bore positioned very deep, a holder (and if necessary a measuring depth extension MTV) corresponding to this large measuring depth MT has to be chosen. When measuring a deep hole bore (i. e. the ratio bore length L to diameter D is over L : D > 10 : 1), the use of a blind sleeve (guidance) is recommended from 30 mm. This helps avoiding the bending of the measuring depth extension as well as the tilting of the measuring sleeve. Blind sleeve 5.2.1.3 Blind hole bore Measuring sleeves with a corresponding small front distance h should be chosen to measure extremely short bores, for example centring shoulders, blind hole bores or offset bores, in case it is necessary to measure close to the bottom of the bore. The holder with retraction is available in order to ease the entering of the plug gauge in the blind hole bore (see chapter 2.2.4). Measuring sleeve 5.2.1.4 Short bore If a very short bore has to be measured and if the length of the insertion chamfer is larger than the length of the bore, it can be useful to proceed without the insertion chamfer (see chapter 2.1.6). 5.2.1.5 Series bores Two requirements should be met to measure series bores, like for example with a plug gauge in a crankshaft housing: OD plug gauge for series bores or deep bores any tilting due to the weight of the measuring instrument, because the centre of gravity is far outside the sleeve, should be avoided the measuring system should always be guided, even if the measuring sleeve is not in one of the Page 25
Selection bores but between two bores. A blind sleeve is useful to meet these requirements. The blind sleeve guides the measuring system as soon as the measuring sleeve exits a bore and until the measuring sleeve is entered in the next bore. Ø D Ø D L L 5.2.1.6 Bore with a tight tolerance Bores with a very tight tolerance require a plug gauge with a consequently higher accuracy. The accuracy can be increased by reducing the undersize of the plug gauge or by using a depth stop (see chapter 4.3). blind bore through bore 5.2.1.7 Bore with a wide tolerance The nominal measuring travel of the measuring sleeve should not be exceeded when measuring bores with a wide tolerance. It is important to note that the measuring error increases because of the increased play between the bore and the measuring sleeve (see chapter 4.3). Ø D1 Ø D2 Ø D1 Ø D2 5.2.2 Form of the bore 5.2.2.1 Cylindricity and roundness deviations The OD plug gauge can be used to determine the bore diameter as well as to measure the roundness or cylindricity of the bore. A depth stop is useful to measure the roundness, in order to ensure a constant measuring depth during the measuring operation. concave bore Ø D convex bore L 5.2.2.2 Polygonal bore It is not possible to measure the deviations in form of a polygonal bore with a two-point measuring method. A three-point design is necessary therefore (see chapter 3.3.6). α 5.3 Material of the bore cone shaped bore 5.3.1 Steel The most common application for the OD plug gauge is the measuring of a work piece made of steel. The measuring contacts of the OD plug gauge are made of tungsten carbide as a standard, since this design is very suitable for this application. Measuring contacts made of ceramic can be used as an alternative, in order to increase the wearresistance. A hard chromed sleeve surface offers an additional protection against wear and corrosion. 5.3.2 Aluminium and other non-ferrous metals A sliding friction between tungsten carbide and alumin- Page 26
Selection ium or other non-ferrous metals, respectively alloys of those, can cause a considerable local heating, so that the aluminium melting point is exceeded (cold soldering). The aluminium sticks to the measuring contact points and a built-up edge appears. This can be avoided either by the use of a lubricant in the bore or by the use of measuring contacts made of a different material. Ruby, ceramic and hard-chromed measuring contacts are suitable for this application. 5.3.3 Grey cast iron When measuring grey cast iron some graphite dust separates from the work pieces. This can spoil the functions of the standard measuring sleeves. The open design, which can be cleaned easily with a blowing device using compressed air, was especially conceived for this application (see chapter 3.3.5). D1 Elliptical bore D2 5.3.4 Synthetic Two important points are to be considered when measuring synthetic work pieces: a) Soft synthetic work pieces are scratch sensible b) The measuring pressure of the plug gauge can cause a deformation of the work piece These problems can be solved with measuring contacts: having an enlarged radius, being hard-chromed or out of Delrin Polygonal bore Ø Di Ø Da 5.4 Surface of the bore 5.4.1 High surface roughness Enlarged measuring contacts are recommended to measure bores which have a high surface roughness. Otherwise, all peaks and valleys are also measured when using small measuring contacts, so that it is not possible to obtain a stable measuring value. 5.4.2 Polished surface Neither the measuring contacts nor the measuring sleeve should scratch work pieces with a very smooth OD-measuring sleeve in open design for work pieces made of grey cast iron Page 27
Selection or soft surface. Delrin measuring contacts prevent work pieces from this damage. 9 M11x0,75 ø 11,9 However Delrin measuring contacts should be calibrated after every measurement, since they are less wear-resistant. SW 10 3,5 33 60 5.5 Special internal profiles The OD plug gauges can be adapted to numerous profile forms, so that the different profile dimensions can be measured. B 5.5.1 Plane parallel distance The measurement of plane parallel distances requires a special OD sleeve design. The flat sleeves of the OSIMESS series can be used for distances up to 40 mm. 5.5.2 Internal taper Cone-shaped bores are defined by the taper angle and by the diameter in a specific measuring depth. For measuring internal tapers with an OD plug gauge, a depth stop, which positions the measuring axis in the defined depth, is absolutely necessary. Therefore, the measuring depth should be defined very exactly. Thus, the design with an integrated depth stop is especially recommended. Measuring sleeves with several measuring axes are available for diameters over 30 mm. Therefore, with the distance of the measuring axes and of the corresponding diameter measurements, the taper is defined precisely. For setting, it is recommended to use a setting ring or a master piece in tapered form instead of a cylindrical setting ring. 5.5.3 Stepped bore A plug gauge with several measuring axes is available to measure all diameters simultaneously, when measuring stepped bores. Depending on the geometry of the work piece, two or more measuring axes are possible, which are offset to each other in a defined angle ( 0 ). The distance between the measuring axes should be minimal 2 mm. It is possible to manufacture designs with two axes in one measuring depth. However, this requires more expenditures. 35 OD measuring sleeve for plane parallel distance α T1 T2 OD measuring sleeve for cone-shaped bores Stepped bore D2 D1 H1 H2 5.5.4 Bore with interrupted circumference According to the width and to the pitch of the seg- Page 28