ZHENYA FASTENER

Jiangsu Zhenya Special Screw Co.,Ltd is one of the leading China tap bolts manufacturers and suppliers, as a professional company, our productive factory is able to produce CE certification tap bolts at both high quality and low price. Welcome to buy discount and cheap, or wholesale products from us.

A full thread bolt with a six sided head

There can be some confusion with identifying various types of hex bolts. We will cover three types: HEX CAP SCREWS, TAP BOLTS and MACHINE BOLTS. All three are very similar looking and can be easily mistaken for one another unless you are familiar with these slight differences.

HEX CAP SCREWS

Hex cap screws are recognized by the washer faced bearing surface under the head. They are partially threaded with an unthreaded area referred to as the "grip". The minimum thread length is measured as twice the diameter plus 1/4" for screws 3/4" in diameter up to 6" long inclusive. These screws are cold form manufactured with rolled threads. When screw length is too short for the minimum thread length rule to apply, they shall be fully threaded.

Screws with a length longer than 6" have a minimum thread length of twice the diameter plus 1/2". The3se larger screws may be either hot or cold headed and the threads may be cut, rolled, or ground at the manufacturer's option. Hex cap screws are available in various grades of steel.

Grade 2

Does not require a heat treatment but may require stress relief. There are no head markings on Grade 2 bolts and therefore are most likely to be confused with machine bolts. To verify check for a washer faced bearing surface under the head. Minimum tensile strength = 74Ksi.

Grade 5

Are heat treated, quenched in oil or water and tempered at 800°F. Look for the three radii markings on top of head. Minimum tensile = 120 Ksi.

Grade 8

Are heat treated, quenched in oil and tempered at 800°F. Look for the 6 radii starburst on top of head. Minimum tensile strength = 150 Ksi.

TAP BOLTS

Tap bolts do not have a washer faced bearing surface under the head. They are fully threaded to just under the radius of the head. Tap bolts are generally available only in Grade 2 steel but can be special ordered in Grade 5 or Grade 8 steel also.

MACHINE BOLTS

Machine bolts are the newest of the hex bolt products. They are partially threaded like the hex cap screws but do not have a washer faced bearing surface under the head. Machine bolts are currently only available in Grade 2 steel.

Hex Tap Bolts, Zinc Plated, A2,A4

The information below lists the required dimensional, chemical and physical characteristics of the products in this purchase order. If the order received does not meet these requirements, it may result in a supplier corrective action request, which could jeopardize your status as an approved vendor. Unless otherwise specified, all referenced consensus standards must be adhered to in their entirety.

Specification Requirements:

Dimensions: ASME B18.2.1 (except thread length)

Material &

Mechanical Properties: Grade 5 per SAE J-429

Thread Requirements: ASME B1.1 UNC & UNF Class 2A, Fully Threaded

Threads must be within 2 times the thread pitch of the head.

Thread acceptance per 6.5.1.4 of ASTM F788

Head Marking: 3 radial lines 120 degrees apart and Manufacturer’s I.D

Finish: Fe/Zn 3AT Per ASTM F1941

Material Test Reports: The MTR must have documented lot traceability, including full

chemical and mechanical figures, to the specification(s) above.