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M-5 Aluminum vs M1 Aluminum


Manufacturers know that when it comes to choosing an aluminum alloy, there are plenty of choices. Aluminum’s versatility and adaptability are part of what makes it so popular. However, it can also be difficult to know which specific alloy will perform best in any given application. This can be especially true when choosing between two similar alloys, such as M1 and M5 aluminum mold plate.

What Are M1 And M5?

M1 was first developed by Alpase in 1988. It is a high density, stable, high strength aluminum plate that doesn’t require heat treatment. It was designed specifically for use in the plastic and mold industries, quickly became a popular choice among manufacturers, and is more cost effective than wrought aluminum and tool steel.

M1 aluminum is especially well suited for high temperatures and features a uniform grain structure, meaning that it has greater consistency throughout its form than many other alloys. It also boasts high machinability, three times higher than steel, thus saving time (and money) during production.

In addition to being uniform, M1’s grain structure is also very tight, so it is metallurgically sound throughout. The process of producing M1 leads to a high dimensional stability and low residual stress. The Brinell hardness remains highly consistent no matter what thickness of plate is being used, and it lends itself to an excellent surface finish. As required, both hardcoat anodizing and nickel coating can be applied.

M5 aluminum, from the 5xxx family of alloys, is another product from Alpase and was developed to help speed up the low volume production of molds. It is considered an affordable alternative that is superior in many ways to wrought and forged aluminum blocks.

M5 plating is both porosity- and grain-free, offering hardness and strength that are highly consistent, even at the maximum thickness. At room temperature, M5 is extremely strong, but it also features increased resistance to thermal fatigue when dealing with high temperatures.

While even in its normal state, M5 is much more corrosion resistant than comparable mold materials, it is also possible to anodize, coat, or texture it depending on the mold applications. The plate also arrives already having a milled surface, meaning there is less machining required.

How Do M1 And M5 Compare?

While similar in many ways, there are a number of specific differences between the two alloys that must be considered before choosing between them. Only a comprehensive comparison can really make clear the specific advantages of one over the other.

For example, when it comes to density, M1 rates at 0.101 lb. per cubic inch, while M5 has slightly lower density, at 0.096 lb. per cubic inch. Meanwhile, M1 has a Brinell hardness of 85 HB, and M5 lists at 70 HB. M1 has an elongation of 7 to 9%, and M5 has a greater elongation of 12 to 15%.

Typically, M1 boasts a tensile strength of 43 KSI and a yield strength of 30 KSI. In contrast, M5 comes in at 41 KSI and 18 KSI, for tensile and yield strength, respectively. The former’s electrical conductivity is listed at 39% and a thermal conductivity of 95 Btu/ft. The latter’s is slightly lower in both categories, with a 29% electrical conductivity and a thermal conductivity of 81 Btu/ft. The modus elasticity for M1 is 10.8 KSI x 10 cubed and it is 10.3 KSI x 10 cubed for M5.

They both have identical thickness and width tolerances. M1 and M5 can be purchased in the following sizes: up to 30-inch thickness, up to 88-inch width, and up to 195-inch length.

What Applications Are They Each Best Suited For?

M1 aluminum can be commonly found in a wide array of applications. For instance, M1 is used for injection molds in which up to 12 cavities are needed. Because of M1’s fast cool-down rate, it offers much higher productivity than steel molds, and M1 molds can be made for about a third of the cost. This also means that M1 molds are more cost-effective when changes will be needed during the engineering process, compared to working with steel or wrought aluminum, which must be rough-machined, heat treated, and then reset for the final machining process.  

Another application for M1 is structural foam molding due to its dimensional stability and uniform hardness. It’s also commonly applied in both R.I.M. and R.T.M. molding thanks to its high thermal fatigue, hardness, polishability, and weldability. Other mold uses include both rubber and blow molding.  M1’s ability to withstand elevated temperatures makes it ideal for composite molds along with high temperature plastics.

There is a great deal of overlap in the general applications for M1 and M5. M5 mold plate has been proven to be a great choice for injection molds, rubber molds, blow molds, and structural foam molds, just as with M1 plate. But in addition, M5 is commonly deployed in applications for vacuum forming tools, compression molds, heating and cooling plates, and semiconductor transfer chambers.

How To Choose Between M1 And M5?

You will need to take the time to carefully compare the distinct properties and characteristics of the two alloys before selecting one for your molding needs. It’s recommended that you take the time to actually test each of the alloys to see how they respond to your particular applications. Thankfully, aluminum alloys are well suited to prototyping scenarios, thanks to their formability, adaptability, and cheap cost.

In the end, no matter which alloy you choose, you’ll rest easy knowing that you are taking advantage of aluminum’s many fantastic properties, including its dimensional stability, weldability, corrosion resistance, strength to weight ratio, and cost efficiency. By decreasing your production costs and increasing your productivity, your final product will be more competitive and more attractive to your customers.


At Clinton Aluminum, we can help you make these kinds of tough choices because our motto is finding the right alloy for the right application. By investing in our people, we’ve built a team that has the knowledge and enthusiasm to be your technical resource partner. To find out more about our commitment to service and value, contact us today.

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