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J_M3_HT10.9 DIN7991 Socket Countersunk CSK Screws

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J_M3_HT10.9 DIN7991 Socket Countersunk CSK Screws

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M3 Self-Colour Socket Countersunk Screws - High Tensile - Grade 10.9
*** ALL SIZES ***

High tensile socket countersunk screws (Grade 10.9) made to DIN7991 standards. Full details and technical specifications below.

Occasionally and for reasons unknown to us, once you have selected options from all the dropdown lists, you may find that if you wish to change your choice of bolt Type/Thread Diameter that you are restricted from doing so - in such circumstances you will need to click on the word "- Select - " that appears at the top of each drop down list before reselecting. Alternatively, please add this page to your Favourites before you make any selections so that you can easily select it afresh. We apologise for any inconvenience this may cause but, unfortunately, this is beyond our control and falls entirely within eBay’s remit.

Technical Data at a Glance

ISO 898-1 Grade/Class 10.9
Manufactured to Standard: DIN 7991
Thread diameter (mm) 3
Standard metric coarse thread pitch (mm) 0.50
Allen key size (mm) 2
Head diameter (mm) 6

*The bolts are fully threaded.
**The bolt length noted in the dropdown box above is the measurement from the top of the head of the bolt to the end of the thread.

Frequently Asked Questions

To further assist you in choosing the bolt(s) most suited to your requirements from the drop down lists above and to avoid the need for you to have to raise several commonly asked questions, please note the following:

  1. The bolts you are looking at on this web page are referred to as screws also and these terms are used interchangeably.
  2. They have a hexagonal hole for use with an Allen key/wrench and are also referred to as socket/hex/Allen drive type. The most effective way, however, of tightening a Grade/Class 10.9 bolt is by using a torque wrench, right up to their 90% proof load (see point 4 below for further clarification of why the figure of 90% is referred to here). Further, because the head of the bolt/screw, when placed in the hole, sits flush with or below the surface of the surrounding material (i.e. CounterSunK) it is occasionally referred to as a CSK bolt/screw.
  3. The bolts are self-coloured (i.e. unplated) and there is good reason for this. The plating process (such as zinc plating) results in some weakening that can compromise high tensile fasteners such as the bolt in question, aside from causing issues with other processes such as welding.
  4. The bolt has an ISO (International Organisation for Standardisation) property classification/grading 10.9 (ISO898-1) which means that it is an alloy steel, quenched and tempered. The bolt has a minimum tensile strength (i.e. the maximum load in tension which it can withstand before breaking/fracturing) of approximately 1000MPa (or 1000N/mm2), the 10 representing the first two numbers of the bolts grading (i.e 10.9).                                                                        The third number of the bolts grading (i.e. the number 9 of 10.9) indicates the point at which the bolt will permanently stretch (i.e. the minimum yield strength) so the 10.9 bolt in question permanently stretches at 90% of its minimum tensile strength (i.e. 1000 x 90% = 900MPa or 900N/mm2).
  5. The thread diameter noted in the dropdown list above is the diameter of the outer thread of the bolt, also known as the major diameter.
  6. The thread pitch specified in the table above is the distance between one thread and the next measured along the length of the bolt in millimeters. All of our bolts have an ISO (International Organisation for Standardisation) metric coarse thread pitch and are the most commonly utilised, as opposed to the less common ISO fine or extra fine metric thread pitches. Although the standard metric coarse thread pitches are well known or can be easily ascertained by simply searching the web, we have set them out in the table above to assist you in your selection of bolt.
  7. A standard is a document that provides requirements, specifications, guidelines or characteristics that can be used consistently to ensure that materials, products, processes and services are fit for their purpose. In Germany, DIN (Deutsches Institut für Normung e.V., German Institute for Standardisation) gives specifications for products, services and systems to ensure quality, safety and efficiency and publishes and updates the valid standards. DIN administers about 29,500 DIN standards, more than 386 of which apply to mechanical fasteners including the bolt in question, which has been manufactured in accordance with the DIN 7991 standard.
  8. All photographs of our products are provided for illustration purposes only and you need to select from the drop down lists the specifics of each bolt you wish to purchase.

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