• Challenge Engineering

CNC Machining Customers: Why Supplying Your Own Material is Risky

Metal and Plastic Bar Awaiting The CNC Machining Process At Challenge Engineering

[Challenge Engineering is an ISO 9001:2015 certified CNC machining company based in Sydney, Australia. We manufacture metal and plastic parts for use in many industries: transportation, mining, rail, energy,

household goods manufactures and more . To find out more visit www.challengecnc.com.au.]

CNC machining is one of the most cost-effective ways of manufacturing advanced, high precision and quality parts. However, despite the relatively low cost of machining, there is often still a temptation to try and save even more.

One common line of thought is to supply the machinist with your own material, thus eliminating the material cost. This may seem like an obvious way to save money, but this article will show that this thinking is flawed.

It is not a good idea to supply your own material, and here’s why:

1. Material Traceability

When purchasing material from any reputable supplier, the material will usually come with Material Certificates, if not this can be requested. The material is often marked with a heat number that links it to the material certificate. The material certificate indicates various things, some of which are indicated below:

  • Heat Number

  • Chemical Composition

  • Strength Test

  • Place of manufacture

All these details serve to thoroughly classify the material. When manufacturing parts for highly regulated industries such as the aerospace, automotive and mining industries it is often required that all parts have the relevant paperwork that can prove the material was produced to certain international specifications or standards.

For example, parts are designed by using material properties that are either nationally or internationally defined. If the actual material used is sub standard, the part can fail unexpectedly far below its design range. Therefore, material traceability is absolutely critical.

2. Material Quality

CNC machine shops often buy the best quality material that conforms to industry standards. With a trusted CNC machining partner, you can be sure that you will get the best possible material when the CNC shop is the one purchasing and sourcing materials. If you supply your own material it is likely that it was not sourced from a reputable supplier and the quality of the material will not be up to scratch.

Another risk with inferior or unknown material quality is that it can suddenly fail during machining. A machinist will not risk damaging their machine if they think the structural integrity of that material is not up to scratch.

3. Cost of Material/Availability

CNC machine shops often buy their material in bulk and therefore get the best possible prices. This means that you will most likely pay more for the same material from the same supplier. Even purchasing your own bulk material will most likely result in a loss because there will always be material wasted, especially if long lengths of stock material are used. Another possible stumbling block is the availability of the materials.

A CNC machine shop not only has access to multiple different suppliers, but they also have relationships with these suppliers and material can be sourced a lot faster.

4. Machine Set up

CNC machinists purchase material that is best suited for their machining set ups, this means that machine shops often have specific work holding equipment mounted to their machines that are best suited to common material sizes and shapes. As such the material you bring might need far more time to set up and prepare for their machines especially if the work holding needs to be changed or if a specialised jig needs to be manufactured to hold the material.

This will result in increased set up times and as a result increased cost. A jig will significantly increase cost because the machinist will want to recoup their full cost of the jig at once, as it is likely it won’t ever be used on another project. The difficulties described above are especially true if the material you provide is of an odd shape.


Depending on where you are situated, sending material to a supplier can be incredibly expensive and time consuming. Shipping metals are extremely expensive due to their large weight. Shipping costs are determined by looking at the volume and weight of a parcel, and weight becomes a significant contributor when sending material via air freight. It can unnecessarily increase the price of your part.

Furthermore, if there is a failure on your part during machining then you will need to send another piece of material and this can significantly complicate matters by not only wasting money, but also wasting time. On the other hand, if a failure occurs in the machine shop and the materials are readily available, the part can be back on the machine before you even know about it.

In Conclusion

It should be quite clear after reading the above points that supplying your own material creates far more problems than solutions, it is unlikely that any financial benefit can be gained by supplying your own material. It is far more efficient to leave the sourcing of materials to the CNC machine shop, as they are aware of all the potential pitfalls of material supply and are in a better position to manage the risk. They also have procurement mechanisms in place that streamline the whole process.

Challenge Engineering is an ISO 9001:2015 certified CNC machining company based in Sydney, Australia. We manufacture metal and plastic parts for industrial equipment manufacturers. To find out more visit www.challengecnc.com.au.

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