AMPCOLOY® 940: Beryllium-Free Copper Alloy for the Plastic Industry

This content has been provided by AMPCO METAL.

How can a copper-nickel-silicon-chromium alloy be your best option for your industrial use?

Alloys with good strength, hardness, and conductivity are often needed for various industrial applications. Electrical (and thermal) conductivity is a well-known property of pure metals, such as copper, yet the latter lacks adequate strength and hardness. Alloying copper with certain metals brings about a good level of hardness, thus satisfying industrial requirements. However, this lowers its conductivity, depending on the type and number of alloying elements.

In the early 20th century, a copper alloy was developed by Michael Corson [1] containing metal-silicides, with forming elements such as chromium, nickel, and cobalt. This alloy substantially enhanced the strength and hardness of the material while maintaining a high level of conductivity.

Based on this, AMPCO METAL patented a copper-nickel-silicon-chromium alloy, namely AMPCOLOY® 940, with a high hardness level and an electrical conductivity exceeding 45%, which is reached by a controlled inclusion of alloying metals and a double aging heat treatment [2]. AMPCOLOY® 940’s composition is shown in Table 1.


Weight composition (%)

Nickel (or cobalt)








Table 1: Composition of AMPCOLOY® 940

AMPCOLOY® 940 shows excellent mechanical properties, with a tensile strength of 544 MPa, yield strength of 475 MPa, and modulus of elasticity of 131 GPa [3]. Its dimensional capabilities vary depending on its shape and manufacturing process. You can read more about those capabilities here.

Advantages of AMPCOLOY® 940 

AMPCOLOY® 940 is an effective alternative to beryllium copper, as beryllium has been classified as a carcinogen [4]. With restrictions that resulted in fewer suppliers and higher production costs of beryllium copper, alloys such as AMPCOLOY® 940 have risen to replace it. 

Of its numerous advantages, AMPCOLOY® 940 has shown a superior thermal conductivity, resulting in reduced temperatures and smaller temperature variations in mould applications. Table 2 shows the eminence of AMPCOLOY® 940 compared to commonly used mould materials in terms of thermal conductivity. 

Mould Material

Thermal Conductivity (Btu/hr/ft/˚F)

Thermal Conductivity (W/(m·K)) at 20 °C




Beryllium Copper






Tool Steel (S7)



Tool Steel (P20)



Tool Steel (H13)



Table 2: Comparison of thermal conductivity of different mould materials.

In addition to that, AMPCOLOY® 940 is easy to machine with all standard machining practices while upholding a hardness of 180-255 HB and high cutting speeds, which allows it to accept and maintain high surface finishes [5].

It also accepts etching and texturing and is compatible with other copper alloys, tool steels and stainless steels in welding applications as it offers composite materials showing enhanced surface hardness.

It does not require further heat treatments and it preserves the intrinsic corrosion resistance property of copper.

Its exceptional thermal conductivity and resistance to corrosion and wear ensure a boosted mould performance and an improved quality in terms of heat removal and extended service life. By efficiently dissipating heat, it guarantees reduced cycle times, controlled post-mould shrinkage, and better dimensional stability.

Its inherent corrosion and wear resistance help prolong the mould's life, which makes it suitable for PVC applications [6].

Production & Applications of AMPCOLOY® 940 

AMPCOLOY® 940 can be manufactured in cast or wrought form, as requested by the customer. It is kept in stock in different shapes, ranging from rod to rectangular bar and plate.

It is used mainly for mould applications. Its outstanding thermal conductivity compensates for irregular part configuration or wall thickness, as the shape, size, and intricacy of the mould determine the location of cooling passages. Mould applications of AMPCOLOY® 940 can be classified into two categories:

  • Blow moulds, which are used to shape and join hollow plastic (or glass) parts. These include blow pins, pinch offs, and mould cavities.
  • Injection moulds, which are used to manufacture parts by introducing molten material into the mould. These include cores, cavities, core and ejector pins, sprue bushings, and hot runner systems.

Other applications requiring good mechanical properties and a high level of thermal or electrical conductivity include electrode holders, seam welding shafts and discs, spot welding electrodes, brake drums for paper winding rolls, and parts for energy engineering. AMPCOLOY® 940’s industrial use spans over various industries, including automotive, plastic processing, resistance welding, and general engineering [7].

Article by AMPCO METAL

Production and Distribution of engineering metal products