Machine Screw
Types of Machine Screw
Pozi Drive
Triangular Thread
Set Screw
Shoulder Screw
Truss Head
Socket Head
CSK Head
Button Head
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The Guide To Machine Screw
Guide 1
What are the Machine Screws?
The term used for a threaded fastener, with or without a head(headless – as in set screw) so designed as to permit it to be properly assembled in a pre-formed internal threaded hole (or capable of forming its own thread) and secured by means of tightening the head.
Guide 2
Parts Name of the Machine Screw
Head: The head of the Machine Screw is performed on the top to provide a bearing surface.
Head Diameter: It is the diameter at the largest extremity of the head
Head Style: The type of head or top that is on the fastener. Such as a Round head or Hex head.
Length: The length of a headed fastener is the distance from the intersection of the largest diameter of the head with the bearing surface to the extreme point.
Shank: The shank is the smooth part of the Machine Screw which lies below the head and above the threads.
Thread: A thread is a triangle profile of a uniform section in the form of a helix in the external or internal surface of a cylinder. This is known as a straight or parallel thread to distinguish it from a taper thread, which is formed on a cone or frustum.
Pitch: Pitch is the distance; measured parallel to the fastener axis between corresponding thread profile points on adjacent threads and on the same axial plane. Used mostly in metric, where it is expressed in millimeters.
Thread Length: the distance between the extreme points of contact on the pitch cylinders or cones for two mating threads.
Guide 3
Machine Screw Material
Carbon Steel- Unhardened
Unless otherwise specified, machine screws shall be non-heat-treated low
carbon steel, such as 1006 through 1022, with a hardness of Rockwell HRB69-HRB100.
Carbon Steel – Hardened
When hardened machine screws are specified, they shall be made from low or medium carbon steel, such as 1018 through 1038, with or without boron, through-hardened to Rockwell C25- C38.
Stainless Steel
When specified, stainless steel screws shall comply with the chemical requirements of ASTM F837.
Guide 4
Designation of the Machine Screw
INCH FASTENERS
Machine Screw shall be designated by the following data in the sequence shown:
(1) product name, including head type and driving
provision and designation of the standard
(2) nominal size (number, fraction, or decimal equivalent)
(3) threads per inch
(4) nominal length (fraction or decimal equivalent)
(5) header point, if desired
(6) material
(7) protective coating, if required
See the following examples:
EXAMPLES:
(1) Slotted pan head machine screws, ASME B18.6.3, 1/4″- 20 x 1-1/4″, hardened carbon steel, zinc plated per ASTM F1941, Fe/Zn 3A.
METRIC FASTENERS
Machine Screw shall be designated by the following data in the sequence shown:
(1) product name, including head type and driving
provision and designation of the standard
(2) nominal size
(3) pitch
(4) nominal length
(5) header point, if desired
(6) material
(7) protective coating, if required
See the following examples:
EXAMPLES:
(1) Cheese head screw ISO 7048 – M5x20 – 4.8 – Tpye Z – ZP per ISO 4042
Guide 5
Inspection of Machine Screws
Vernier Caliper
Will use vernier calipers to measure the basic dimensions of Machine Screw, like head diameter/height, length and so on.
Thread Plug&Ring Gauge
Will use thread plug&ring gauge to test GO/NO GO, including metric thread (Coarse&Fine), inch thread (UNC&UNF).
Depth Gauge
Will use depth gauge to measure the depth of screw slot, such as hexalobular slot, cross recess, and other slots.
Coating Thickness Gauge
Will use coating thickness gauge to measuere the thickness of the coating layer, such as zinc electoplated.
Guide 6
Packaging of Machine Screws
Usual Packaging
Label: black text on white, no pattern and barcode
Carton: standard double corrugated neutral carton, bulking packing, maximum load bearing: 25kg per carton
Pallet: Europe Fumigation Pallet, 36 cartons per pallets, Width 800mm x Length 1200mm
Guide 7
Production Time of Machine Screws
Flow 01: Need 3 Days – Analyze Customers’ PO and Place Orders to the Factory
Flow 02: Need 10 Days – Purchase the Raw Material
Flow 03: Need 15 Days – Make Production Plan and Wait for Starting Production
Flow 04: Need 15 Days – Formal Mass Production
Flow 05: Need 7 Days – Send Out to Do Heat Treatment (if exist)
Flow 06: Need 7 Days – Send Out to Do Surface Treatment (Finish)
Flow 07: Need 7 Days – Packaging, Make the Shipment
Total Time: 60 Days to 70 Days
Guide 8
Inquiry Required Content
Let us know who you are, and we can contact you in time.
We will give you a more reasonable price.
Let us know your needed product well.
Let us know if the products need to do the heat treatment.
Zinc Electoplated or Hot Dip Galvanized Coating or Zinc Flake Coating…
Our MOQ is about 1 pallet (900KGS) per size.
If it is a customized package, we will send the carton/label to you by courier for confirmation before packaging.
We will make a more suitable production plan for you.
FOB (We usually quote based on FOB ), CIF, FCA
This information is important before mass production. We will adjust the production plan according to your requirement.