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Materials selection for CNC machining price.

Materials selection for CNC machining price.

Material selection can impact the CNC machining price.

Material selection is critical in determining the overall functionality and cost of the CNC machined part.

There is a big range of materials machined to be used for parts.
Choosing the right materials and material grade will determine the life time usage and the wear factor.

Examples of most used materials selections.

As a guide here are some of the most popular materials used for CNC machined parts.

  • Alloy Steel
  • Aluminum
  • Brass
  • Copper
  • Plastics
  • Stainless Steel
  • Steel
  • Titanium
  • Tungsten

Each of these materials could have hardness grades and different composition.

Cost implications in CNC machining price

Material selection is critical in determining the overall functionality and the cost of the part.

You must choose important material characteristics—hardness, rigidity, chemical resistance, heat treat-ability, and thermal stability.
Just to name a few you will need to nominate this in your quotation request.

Why does the materials selections effect the price?

The price is calculated on the materials cost and the machine time.
Softer metals, like aluminum and brass, and plastics, machine easily with less CNC machining time.
So the price is lower.
Softer materials take less time to remove material, which reduces the time and CNC machining cost.

The cost is higher for harder materials, such as stainless steel and carbon steel.
These materials  must be machined with slower CNC machine spindle R.P.Ms and CNC machine feed rates.

What is an example of the differences for material selections?

Material Selection in time needed to make the custom machined parts.

An example is, generally aluminum will machine about four times faster than carbon steel.
Machining aluminum generally is eight times faster than stainless steel.

Explain more about the different grades.

Material properties for machining

Material grades also has an effects the cost CNC machined parts.

While there is an huge list of grades, a simple example of material material cost differences just for aluminum is as follows.

For a cost comparison example, 6061 aluminum bar stock is approximately half the price per kg than the cost of  aluminum plate.
The cost of 7075 aluminum bar stock can be two to three times the cost of 6061 bar.

This has a huge impact on the end cost of the parts, since it impacts the time needed to machine the parts.

We advise you choose the grade and type of the materials carefully. We are always ready to offer our professional recommendation for materials to assist you to get the most cost effective outcome.

Tolerances effect prices!

Tolerances effect prices!

Can tolerances effect prices for custom machined parts.

Tolerances, effect prices of your custom machined parts in many ways.
Whether you need a one-off test part, low-volume prototype order, or 100, 000 custom machined pieces!

Tolerance can be determined by the designer based on the form, fit, and function of a part.
While precision is our very important, you should consider the tolerance needed for the custom machined parts carefully, since it has a huge bearing on your custom parts cost.

Why would the cost be different, based on the tolerance?

cncxpress tolerances effect prices
Machining to minute tolerances.

Keep in mind that tighter tolerance can result in additional cost, due to increased scrap, additional machining time or special tools required.

Tolerances also effect prices because it means longer cycle times if the machine needs to slow down to hold the tighter tolerances.

It is possible that the costs can be more than double the standard tolerance.

Depending on the tolerance of the custom part and the geometry associated with it.
Tighter tolerances should only be used when it is necessary to meet the design criteria for the part.

How to Reduce CNC Machining Costs?

Unless specifically called out by the designer, the standard tolerance used is ±.005 in. for metal parts and ±.010 in. for plastic parts.
Furthermore, overall geometric tolerances can be applied to the drawing for the part.

If tighter tolerances (less than the standard, e.g. ±.002 in.) are required, please let us know which dimensions require a tighter tolerance range. As a point of reference, a piece of paper is about 0.003 in. thick.
Remember based on the geometric tolerance and type of tolerance applied, cost may rise due to increased inspection times.

The following are some of the reason prices vary because of tolerances.

  • Longer set up time for the machine.
  • The need to change the tooling regularly.
  • The extra number of passes to get the exact tolerance.
  • The additional waste.
  • In many cases the necessity to use higher grade materials.

We are here to assist you if you need any advice which tolerance is right for you.

Careful planning and thinking about the project and the tolerances required. 

Please discuss any concerns you have with us and let us get you the best cost saving.
Also in some cases make the part easier to use.