ASME B107.28M:1997 pdf download ELECTRONIC TORQUE INSTRUMENTS
1 SCOPE
This Standard is intended to cover the general, dimensional, and functional characteristics for manually oper.ated electronic torque instruments used for controlof the tigitness of threaded fasteners. It also coversrequirements for endurance, torquc value ranges.andaccuracy for these iorque instruments. it is not intendedto describe products infrequently utilized or those designed for spccial purposcs.
2 CLASSIFICATION
The following fypes and classes of electronic torqueinstruments are covered in this Standard.
Type I Torque Instruments
Class A-Integra! HcadClass B- Interchangeable Head
3 NORMATIVE REFERENCES
ASME B107.4M-1995，Driving and Spindle Ends forPortabie Hand,Impact, Air, and Electric Tools (Percussiun Tools Excluded)ASME B107.10M-1996，Handles and Attachments forHand Socket Wrenches – inch and Metric SeriesASTM E 18-1994,Standard Test Methods for RockwellHardncss and Rockwell Superficial Hardness of Metallic Matcrials
4 REQUIREMENTS
4.i iiiustration
The illustration shown herein is descriptive and notrestrictive. and is not intended to preclude the manufacture of an electronic torque instrument which is otherwise in accordance with this Standard.
4.2 Design
The torque instrument shall be capable of clcctronically indicating the torque applied through the usc ofa transducer and digita! display. The torque valucreadout shall have a minimum of 0.125 in. (3.18 mm)high characters and shall be visible at a viewing angleup to 45 deg. from normal. It shal! have an integralpower supply capable of meeting the requirementsspecified in para. 4.12.
4.3 Finish
Exterior surfaccs of the torque instrument sjall besmoothly finished. Sharp edges and corers capable ofcausing injury sha!! be removed and parts subjectto corrosion shall be appropriately protected. Minorblemishes shall be permitted provided they do notdetracr substantially from the appearance or operationof the torqtie instrument. Protection from environmentaldamage shall be provided by suitable coatings or trans-parent cover.
4.4 Coatings
Coatings shall be tightly adhcrent, uniform in appear-ance, and free from defects that would prevent fullcompliance with the requirements of this StandardThey shall protect the base metal from corrosion undcruse and storage conditions norma!ly associated withhand tonls, and they shall not peel, crack, or blisterin such use or storage. Minor blemishes shall bepermitted provided they do not detract substantia!!y fromthe appearance or operation of the torque instrument.Cadmium plating shall not be used as a coating
4.5 Drives
4.5.1 Plain Square Drive, Thc drivc tang shallconform with the requirements of ASME B107.4MThe square drive shall be oriented so that any two ofthe opposite flats shall be parallel within 5 deg. of thelongifudinal axis of the instrument, The drive ball sha!!be located as shown in Fig. 1.
4.5.2 Ratchet Drive. The operation characteristicsof the ratchet when’incorporated in a Type I torqueinstrument sha!! conform with the requirements ofASME B107.10M
4.6 Capacity
“The highest indicated value of the torque instrummentshall not exceed the limit specihed in Table 1. Thelowest indicated value shall be no grearer than 20%of the highest indicated value.