Steel

Good machinability + Excellent electrical conductivity

Introduction

An alloy made up primarily of iron and carbon, steel is known for its high tensile strength and low costs. The combination of these characteristics has made it a ubiquitous material in the construction, infrastructure, automotive, maritime, tooling, manufacturing and defense industries, among others.

Steel Subtypes

1018 Low Carbon Steel

1018 low carbon steel has good machinability, weldability and formability properties. Though not the strongest steel, it is widely used for fabricating parts such as fixture clamps, mounting plates and spacers. 1018 low carbon steel can be heat treated to achieve surface hardening.

Tensile Strength	Elongation	Hardness	Maximum Temp	Manufacturing Process
60,000 psi	15%	90 HRB	1700ºF	CNC Mill, CNC Lathe

4140 Alloy Steel

4140 alloy steel is a low alloy steel containing chromium, molybdenum and manganese. In terms of mechanical properties, it has good strength and toughness, making it ideal for a variety of industrial applications. 4140 alloy steel is more challenging to form and weld than some other alloy steels. The aluminum alloy is commonly used instead of Aluminum 2024 as it has similar performance and superior strength.

Tensile Strength	Elongation	Hardness	Maximum Temp	Manufacturing Process
165,000 psi	18%	99 HRB	1110ºF	CNC Mill, CNC Lathe

4340 Alloy Steel

4340 alloy steel is a low alloy steel containing chromium, nickel and molybdenum. It can achieve high strength and hardness with heat treatment and is characterized by good toughness, fatigue strength and wear resistance. 4340 alloy steel has good machinability, formability and weldability.

Tensile Strength	Elongation	Hardness	Maximum Temp	Manufacturing Process
161,000 psi	13.2%	99 HRB	1110ºF	CNC Mill, CNC Lathe

Surface Finish

Electroplating

Electroplating can be functional, decorative or corrosion-related. Many industries use the process, including the automotive sector, in which chrome-plating of steel automobile parts is common.

Painting

Painting the surface of a part improves its aesthetic appearance and can provide brand recognition to consumers. In addition, painting can have a protective effect on parts.

Polishing

Polishing is the process of creating a smooth and shiny surface, either through physical rubbing of the part or by chemical interference. The process produces a surface with significant specular reflection, but in some materials is able to reduce diffuse reflection.

Powder Coating

Powder coating forms a durable, wear resistant and corrosion resistant layer on the surface of parts. Powder coating can be used to apply colors to parts and is compatible with any metal.

Manufacturability

Tolerance

- Standard: (+/-) 125 μm -Achievable: (+/-) 100 μm , (+/-) 50 μm

Wall Thickness

- The minimum wall thickness should be at least 1 mm for machined parts. - 2 mm is suggested for better strength and 2.5 mm for a rigid wall.

Pocket depth

- Pocket depth should be up to 3 times the diameter of the end mill

Engraving

- Engraving is preferable to embossing - For clear, legible text consider fonts such as Arial or Gothic - Design letter strands with a width of at least 2 mm

Internal Radii

- The minimum internal radii possible is 1 mm - In general, internal radii dimensions depend on the depth of pocket being milled

Holes

- Use standard drill bit sizes - Minimum of 1 mm in diameter

Threads

- Use standard metric inserts - Smallest threaded insert possible is M2

Design Recommendations

Alloy steels integrate different alloying metals to achieve varying degrees of strength, hardness and wear resistance. This means that alloy steels have different properties in terms of machinability, weldability and even corrosion resistance. Typically, low carbon steels are known for their good machinability.