In selecting the right material for your application. It is important to understand material characteristics. Best to consider the weight, hardness, magnetism, corrosion resistance and conductivity of the material.
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First of all, you have to consider the key purpose or application for your project. Choose the fastener (screws or nuts) that match your requirement(s). Then, we can consider the head type, thread, material and surface treatment of different screws.
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We have to consider the color appearance, rust-resistance and environment for the application of the screw.
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Basically, the difference between a cap screw and a bolt is the way in which these fasteners are installed. Technically, a bolt is installed by turning a nut to tighten the fastener, while a cap screw in installed by turning the head of the bolt to assemble and tighten. In other words, a screw is a tapered fastener that mates with an existing thread or creates its own thread in a material as it turns. A bolt is a non-tapered fastener that uses a washer and nut to hold objects together.
The key function of washer is to reduce the contact surface area of the connected part. Thus, reducing the pressure per unit area and protecting the surface of the connected part from damage. Washers protect the surface from damage during installation. They distribute the pressure and prevent the fastener from moving or corroding. The spring washer can also play a role in preventing the nut from loosening. Operating without flat washers or spring washers can dramatically reduce the lifespan of how your product is put together.
Both types of screws can cut or penetrate through sheet metal surface.
Self-Tapping Screw – a screw for securing thinner sheet metals and other substrates that cuts its own thread, but usually requires a predrilled or pre-punched hole. Thus, Self tapping screws tap their own head, so they need a pilot hole slightly smaller than the screws diameter. Tapping screws drill a pilot hole into wood or another soft material. Self-tapping screws are ideal for all sorts of materials such as wood, metal and brick.Not all tapping screws have a pointy tip, some will be blunt, notches on the thread for thread-cutting or flat.
Self-Drilling Screw – also know as TEK screws, these screws work as both a drill bit and a fastener. It is a screw that can, well, self-drill through various gauges of metal materials without predrilling. Commonly used when doing frame work on cars, or attaching sheet metal to a metal frame. TEK screws have much variance in types and uses than tapping screws.
The most basic difference between the grades of steel is the presence of molybdenum in stainless 316. Stainless 316 contains more nickel than stainless 304, while 304 contains more chromium than 316. Stainless 304 usually consists of 18% chromium and 8% nickel.
SUS304：Good corrosion resistance, heat resistance, low temperature strength and mechanical properties, good malleability & workability such as stamping and bending. Widely used in household products; tableware, cabinets, indoor pipelines, water heaters, boilers, bathtubs, auto parts, medical appliances, building materials, chemical & food, agriculture industries and ship-building parts.
SUS304L：Austenitic stainless steel grade,with good welding performance, excellent corrosion resistance and heat resistance; Excellent low temperature strength and mechanical properties. No heat treatment hardening properties (non-magnetic, applicable temperature- 196 ~ -800℃)
SUS316：The corrosion resistance and high temperature strength and work hardening mechanical properties are particularly good. Suitable for seawater equipment, chemistry, dyes, papermaking, oxalic acid, fertilizer production equipment, photography, food industry and coastal facilities.
SUS316L：Mo (2-3%) is added to the stainless steel, so it has excellent corrosion resistance and high temperature strength; SUS316L has lower carbon content than SUS316, has good welding performance, and has better intergranular corrosion resistance than SUS316; elevated temperature creep strength. It can be used under harsh conditions with good work hardening properties. Suitable for sea water equipment, chemistry, dyes, papermaking, oxalic acid, fertilizer production equipment, photography, food industry, coastal facilities.
SUS410：(Mada San series), high strength, high hardness (magnetic); poor corrosion resistance, not suitable for use in severely corrosive environments; low C content, good workability, surface hardening through heat treatment.
SUS420 (round rod)：(Mada San series), high strength, high hardness (magnetic); poor corrosion resistance, poor processing and formability, good wear resistance; can be heat treated to improve mechanical properties. It is widely used for processing knives, nozzles, valves, rulers, and tableware.
SUS430 (plate or panel)：Low thermal expansion rate, good molding and oxidation resistance, suitable for heat-resistant appliances, burners, home appliances, class 2 utensils, kitchen sinks. Relatively low price, good workability; good corrosion resistance, typical non-heat treatment hardenable ferritic stainless steel.
Surface Corrosion : Formed by the wear and tear of the surrounding environment, such as sand, salt in the air, causing the underlying material to be exposed to oxygen and cause oxidation, forming the so-called rust.
Local or Diffusional Corrosion : When the outer surface layer of a particular part of the screw falls off and causes oxidation in a certain place.
Contact Corrosion : This is caused when different materials come into contact during the electro-chemical process.
Stress Corrosion Cracking : When small cracks appear on the screw junction, corrosive chemicals will accelerate the formation and make the material of this part rust.
Pressure Corrosion : Usually refers to the hydrogen embrittlement of the environment, which is caused by hydrogen infiltration in the surrounding environment when the screw is under pressure. Surface corrosion can also allow hydrogen to penetrate the screw.
RoHS stands for Restriction of Hazardous Substances. It is an environmental protection that mainly regulates the material and process standards of products. This was passed in 2003 and took effect on July 1, 2006. All products entering the European Union will be restricted by this directive. RoHS compliance prohibits the content of more than 0.1% by weight of lead (Pb), mercury (Hg), hexavalent complex (Cr), polybrominated biphenyl compounds and their compounds, polybrominated diphenyl ether compounds (PBB) and their PBDEs (PBDE) ) And 0.1% cadmium (Cd) electronic products enter the EU market.
MOQ depends on the product specifications. The first step is to determine whether your requested item is a general standard specification product or a non-standard, customized specification product, and whether we have stock available in our inventory warehouse.For standard items, the MOQ will be according to our normal packaging details per bag / per cardbox box or per carton. Depending on dimension size of the item, normally the MOQ for each item is 50,000PCS per size item.
For domestic Taiwan Customers, we offer FREE Shipping if the total Purchase Order value exceeds NTD $3000 per order. For domestic Taiwan Customers, if the total PO value is less than NTD $3000, the shipping cost will be NTD $100 flat rate (only local delivery in Taiwan area) For overseas Customerm if the total PO value exceeds Minimum Order Amount (MOA) of USD $3000, we can deal in FOB or CNF or CIF Incoterms (FREE local handling charges and customs clearance fee) For overseas Customer with total PO value less than USD $3000, we can only deal in EX-WORK Taiwan terms. Otherwise, additional handling and customs clearance fee total of USD $200 is required to be paid by the Customer against PO.
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1. Material for your requested item?
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3. Require heat treatment(Hardening) ?
4. Require what type of Surface Treatment?
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