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Fasteners Information
RENSON / 2017-04-14
Fasteners are a kind of mechanical parts that are used for fastening connections and are very widely used.Fasteners are widely used in the industry. Including energy, electronics, electrical appliances, machinery, chemical industry, metallurgy, tooling, hydraulic and other industries. In a variety of machinery, equipment, vehicles, ships, railways, bridges, buildings, structures, tools, instruments, chemicals, instrumentation and supplies, etc., can see a wide range of fasteners, is the most widely used mechanical base. It is characterized by a wide variety of specifications, performance of different uses, and standardization, serialization, generalization of the degree is also extremely high.

Fasteners Materials Type


The predominant material, metal or elements in a fastener


Stainless Steel

Brass & Bronze


Steel is the most common material used in fasteners.

Low carbon steel

Hardened Steel

Alloy Steel


Low carbon steel for general use is usually known as iron, steel. Some people also called it mild steel. There are tiny different of the chemical elements. Mechanical property  class is 4.8 (metric measurement) which equials ASTM/ANSI grade 2. Relatively inexpensive, but is the least corrosion resistant. Also known as Carbon Steel.


Hardened Steel is often used for a medium or high carbon steel that has been heat treatment and then quenching followed by tempering. How hard the steel will become depends on the amount of carbon present in the metal. The hardened steel fasteners we often called which means property class 8.8 (ASTM/ANSI grade 5) .


Alloy Steel is alloyed with a variety of elements to improve its mechanical properties(strength, hardness, corrosion resistance...).  Mechanical properties refer to class 10.9 (grade 8), class 12.9, class 14.9 and etc.


Stainless Steel an iron based material with a minimum of 10.5% chromium.


This material is known for its corrosion resistance and has varying strengths depending on the amount of chromium and nickel alloy. Making it suitable for outdoor and marine applications. The chromium forms a protective layer when exposed to oxygen, keeping the steel underneath from corroding. There are over 150 grades of this material with the 304 and 316 series being the most common. Which is more expensive than zinc plated fasteners.

Stainless Steel 316/316L (A4)

Stainless Steel 304/304L(A2)

Differences betweem 304 and 316.

18-8 Stainless Steel is nominally 18% chromium and 8% nickel, with the remainder being mainly iron. It does however also containother elements, but at very low levels, it is also known as 302 or 304 grade stainless steel.

Stainless Steel 410

Stainless Steel 201

Stainless 401

What do you need to know?



Brass is a metal alloy made of copper and zinc. By comparison, bronze is principally an alloy of copper and tin. However, bronze and brass also include small proportions of other elements.


Brass has higher malleability than bronze or zinc. The relatively low melting point of brass (900 to 940 °C, 1652 to 1724 °F, depending on composition) and its flow characteristics make it a relatively easy material to cast. The density of brass is 8.4 to 8.73 g/cm³.

Corrosion-resistant(CR) brass for harsh environments. Much more expensive than steel.

This material has a distinctive bright golden coloring and is primarily used in aesthetic settings or in applications where low friction is necessary. As an electroplated finish it is nonmagnetic and resists corrosion well. Often used when sparking is an issue. It has excellent cold working (forming at room temperature) properties. Used in locks, gears, doorknobs, plumbing, electrical applications and musical instruments.

Mechanical Properties          

Tensile Strength Ultimate: 338-469Mpa(49000-68000psi)

Tensile Strength Yield: 124-310Mpa(18000-45000psi)

Elongation: 53%




 Nylon Fasteners  Aluminium Fasteners  

About the feastures of the nylon is known well.

Here we are talking about the Nylon Fasteners.

Why we chose the nylon as the material of fasteners? Here are the reasons below(the sample is nylon 6):

1. More compact molecular structure.

2. Better weathering properties and better sunlight resistance.

3. Soft hand feeling which is different from the metal fasteners and it is hardened.

4. High melting point (256 ° C/492.8 ° F).

5. Superior colorfastness.

6. Excellent abrasion resistance.


Want to know more tensile strength, bending properties, impact strength, creep properties of the mechanical properties of Nylon?

Aluminium is the most widely used non-ferrous metal. Aluminium is almost always alloyed which markebly improves its mechanical properties. Especially when tempered.

Why we use aluminium as the material of our fasteners?

Because its mechanical properties and the chemical properties below:


Corrosion Resistance can be excellent because a thin surface layer of aluminium oxide forms when the bare metal is exposed to air. effectively preventing further oxidation, in a process termed passivation. The stronger  aluminium alloys are less corrosion resistant due to galvanic reactions with alloyed copper. and etc. So, aluminium fasteners perfect.

 The term "acrylic" is used for fasteners that contain a substance derived from acrylic acid or a related compound. Most often it is used to describe a clear, glass-like plastic known as poly methacrylate(PMMA).


Acrylic as the material of the fasteners because its advantages of much more impact resistant and therefore safer.  It also insulates better, potentially saving on heating bills.

Another advantage of acrylic is lightweight and makes it a better choice for projects where weight is an issue. Acrylic is visible. Looks very beautiful in joints.




Head Marking & Fasteners Type

Common Fasteners Types Chart

Bolts & Studs                             



Washers & Others                      

Hex Bolts

Hex Nuts

Machine Screws


Flange Bolts Hex Structural Nuts Socket Screws Plain Washers
Square Head Bolts Locking Nuts Set Screws Sealing Washers
Eye Bolts Acorn Nuts Drywall Screws Spring Lock Washers
Hex Structural Bolts

Flang Nuts

Wood Screws Square Washers
U-Bolts Coupling Nuts Tapping Screws Beveled Washers
Round Head Bolts Slotted Nuts Wing Screws Toothed Lock Washers
CSK(Countersunk) Head Bolts Wing Nuts Knurled Screws  
T-Head Bolts Square Nuts Drilling Screws  
Wheel Bolts Round Nuts    
Double End Bolts T-Nuts    
Thread Rods Wheel Nuts    



Fasteners Grade(US) and Class(Metric) refer to the mechanical properties of the fasteners material. Generally, a higher number indicates a stronger, more handened fasteners. But also more brittle.

US and metric bolt head markings


Drive and Head Style


Phillips Drive

Frearson Drive

Pozidriv Drive

Slotted Drive

Combo Drive

Hex Socket Drive

Square Drive

Torx Drive

Phillips Drive

is common in screws. It's prone to cam-out.

 Frearson Drive

is very similiar to phillips but less prone to cam-out.

Pozidriv Drive

is similiar to phillips and also less cam-out.


Slotted Drive

is common in screws and prone to cam-out.

Combo Drive

can be used for both phillips and slotted drive tools.

Hex Socket Drive

Also called Allen drive. it's prone to cam-out.

Square Drive

is resistant to cam-out. Can be installed by hand.

Torx Drive

is less prone to cam-out and compact to drive.



Hex heads

Pan heads

Flat heads

Round heads

Oval heads

Truss heads

Socket heads

Button heads

Hex Heads

are the most common used  and tightened with a hex wrench.

Pan Heads

have a domed head above the surface.



Flat Heads

are installed in a countersunk(csk) hole for a flat surface.


Round Heads

is a higher domed heads and used for decorative purposes.

Oval Heads

is a lower domed and CSK heads used for decorative purposes.

Truss Heads

is slightly domed with a wide head for extra large surface aera. 

Socket Heads

has both smooth and knurled sides with a socket drive.

Button Heads

medium domed heads with a hex socket drive.



Measuring Diameter

TPI and Thread Pitch

Length Measurment

How to choose fasteners

 Fasteners diameter measurement

Normally, the diameter is measured on the ouside of the threads. We also called it outter diameter.  If our fasteners is 3/4'' diameter which means outter diameter.


US diameter under 1/4'' are given as numbers(e.g.#10) in stead of inches.









 thread counts per inch(TPI)

TPI(Threads Per Inch)(US) which specify Thread counts.  Which means the thread density of the machine threaded fasteners. Please see our US Coarse and Fine Threads Per Inch (TPI)


For metric fasteners specify as thread pitch in mm. Please see our
Metric Coarse and Fine Thread Pitch Table


The TIP or Pitch we normally sell is coarse(standard). There are fine and super fine threads are available.






fasteners length

Length is usually measured from the shank end of the fasteners to where the shank is assumed to start.

Countersunk(CSK is abbreviation) fasteners are measured overall.

Non-countersunk fasteners are measured from the bearing surface(under the head) to the shank end point.


How to choose fasteners

Diameter tolerance and TPI is extremly important to guarantee you nuts and washer sizes are fit to the bolt.


Screw Threads 

Screw Threads — UNC, UNF and UNEF

Inch Threads vs. Metric Threads

Tolerances Inspection Tools-Go/No Go Gauge

US(Inch) Sizes and Metric Sizes Interchangeable Table

Metric Coarse and Fine Thread Pitch Table

US Coarse and Fine Threads Per Inch (TPI)


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