1. Use environment
Ordinary digital calipers should not be used in humid (relative humidity greater than 80%), contact with water or conductive dust. The digital caliper with IP65 and IP67 protection function can be used in the environment. If the use environment is humid but little contact with water, you can choose IP54 digital calipers with lower protection level, whose price is slightly higher than that of ordinary digital calipers.
2. Accuracy requirements
The resolution of ordinary digital calipers is 0.01mm, and that of high-precision digital calipers is 0.005 and 0.001mm. The limit error measured according to international standard (ISO / DIS 13385-1996) is as follows:
Measurement range mm limit error mm
3. Performance and function
Special digital caliper:
Groove Caliper – measure the groove diameter, width and position in the hole;
Special claw Caliper – lengthening claw, sharp claw, thin claw, oblique claw, needle claw, column claw, long and short claw, telescoping claw, rotating claw;
Thread pitch Caliper – measure the pitch diameter of internal and external threads;
Gear Caliper – measure the tooth thickness and common normal line of the gear;
Keyway Caliper – measure the symmetry, inclination and depth of keyway;
Saw Caliper – measure the tooth division of saw blade, hard quality surface, clamp and measure once, accurate and efficient;
Tube wall thickness caliper – measure the wall thickness and bottom thickness of tubular, bowl and bottle objects;
Wide caliper caliper measuring the diameter of wire rope or soft material such as sponge and foam plastics.
There are also special digital calipers for measuring deep hole, small hole, large diameter, circular defect radius, taper head or taper hole diameter.
4. Display function
Length unit conversion – mm and inch can be arbitrarily converted;
Data hold – keep the displayed value unchanged;
Tolerance setting tol — the measured dimension limit can be set, and the measurement result is qualified or out of tolerance with symbol;
Tracking Max — only the maximum value in the measurement process is displayed;
Preset value set — preset measurement start value;
Absolute measurement ABS – the relative measurement value (small increment of relative standard value) can be converted into absolute measurement value;
Data output – the special connection wire with interface provided by the manufacturer can be used to send the measurement data to the computer for processing.
5. Quality and brand
Brand represents quality and price, and the quality and price of world famous brand products (imports) are higher. In order to reduce the cost, they have turned to Chinese production, and the quality gap between them and domestic high-quality calipers is narrowing, while the price is still more than two times higher than the latter. It is more suitable to choose according to the ratio of performance and price.