How do I know if a custom machining tool is right for my application?

When providing a quote for a new part with complex shape and geometric detailing, care must be taken to come up with a proposal that will be cost-competitive yet still profitable. Part of that assessment consists of a decision on your tooling capabilities. Will off-the-shelf tools suffice, or would a custom machining tool solution be a better option? This article will discuss some of the points to consider when selecting tools for custom jobs.

1) In-house tool design capabilities

A small company faced with a novel product to manufacture will almost certainly want to consult with a machine tool design specialist. Even a company within a sizable engineering group may need help if the group is working at or near capacity. The specialist company will likely have experience with all of the factors your team is wondering about, including:

  • Would a polycrystalline diamond (PCD) tool be a better choice for this application?
  • Is internal tool cooling required?
  • Can a combination tool be created that would shorten the production cycle time?
  • Is your CNC machine rigid enough and powerful enough to take advantage of higher material-removal rates?
  • With a brand-new tool, what’s the best starting point for determining machining parameters?

Leveraging outside help to get the best solution can save time and production heartaches, as well as adding to your tool design team’s expertise and experience in preparation for the next job.

2) Availability of standard tools for the job

If tasked with deciding on whether to call in outside talent for help with tool selection and design, here are a few of the questions to answer:

  • Is there a tool with the right shape and size to make the cuts needed?
  • Does the geometry of the part lend itself to operations by standard tools?
  • Could a specially designed tool allow combination operations that save time?
  • Can all customer dimensional and performance requirements be met using conventional tools?

Working together with a machine tool design specialist can help answer all of these questions.  For example, consulting on custom porting tools can result in a dramatic improvement in cycle time by replacing separate piloting, drilling, spot facing, and other complex shaping operations with one tool carrying specialized cutters for each task.

3) Work material

The advent of stronger materials containing more abrasive particles has made even many non-ferrous materials a challenge to machine. Examples are aluminium with high silicon content, metal matrix composites or carbon-fibre-reinforced polymers. Custom tools are often the perfect solution to material-based machining difficulties. 

PCD tools are an excellent answer for the materials described above. However, PCD tools would not be the right choice for machining steel parts. This is because, above a certain temperature, a chemical interaction occurs between the carbon that makes up the diamond tool and the iron in the steel. This interaction forms iron carbides and degrades the tool very quickly. A careful study of the job by a custom PCD tooling specialist can help decide on how to pick tools for custom jobs.

4) Cost/benefit analysis result

The quotation process is all about a manufacturing company making the best estimate of the right process and tools to profitably manufacture a quality part at a competitive price. This often has to be done with limited information, drawing on the experience base of in-house experts. Every company has its own decision-making procedures, but some of the high-level cost-benefit factors that must be considered are:

The project timeline

Creating custom tools starts with:

  1. An analysis of the product CAD (Computer-Assisted Design) drawings
  2. A review of the tentative process plan
  3. Evaluation of tooling options
  4. Design and manufacture of the actual tools 

Stepping through this process takes time initially, but should pay dividends during series production by reducing tool replacement (better custom tool wear profile), changeover times (combination tools), and faster cycle times (faster feed rates).

Production volume

If the contracted production volume is large, custom tooling that squeezes every last efficiency out of the machining process makes sense.

Up-front versus ongoing costs 

Just as custom tools may require more planning time early in the project, they may require more up-front money to be spent, both for tool design services and the custom tools themselves. The estimator must balance these potential costs against the opportunity to recoup the money spent later when proper tool design and selection safeguards your process against unexpected tool breakage and fast tool wear, both of which can be very expensive to remedy.

Customer requirements

Theoretically, a customer should only care about the quality of the part produced using their specified material and dimensions. Custom tools may help meet those requirements. In some cases, customers may impose process requirements as well, and this must also be taken into consideration.

How to pick tools for custom jobs

For a low-volume, simple machining job on familiar material, a standard tool that you are accustomed to using is probably good enough. Even so, it may be worth consulting a specialist company like Exactaform for the most up-to-date perspective on how to pick tools for custom jobs. But if you’re working on difficult, novel materials, and preparing for a large production run, Exactaform’s tool designers can give you a leg up on your competition by advising you and helping to select precisely the right tool, with the right cost/benefit and the right performance for your specialised job. Contact an Exactaform representative today.



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