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Which is better, 3D printing or CNC machining?

The age-old question, “Which is better, 3D printing or CNC machining?” I have asked each product manager 5 questions. Each igus product group is covered by a manager, Dean Aylott (DA) is the 3D printing Product Manager and Alan Hicks (AH) is the Product Manager for stock materials.

Let’s see how the answers differ when asked which is better 3D printing or CNC machining?

If a customer wants a custom part, how do they choose between 3D printing or CNC machining?

DA: Great opening question…. So, I would typically need to know a little bit more about the application. What are the loads, speeds and environmental implications? What is the part doing and where is it located? From there I can look at a material choice to best suit the application which may or may not rule out or point to a specific additive manufacturing method. FDM, SLS or moulded. Sometimes a material requirement is such that moulding or machining from bar and plate is required. We cannot print all igus® materials in the same way as they cannot be extruded

AH:”I agree, great question. Choosing a manufacturing process between 3D printing or CNC machining really depends on the size and complexity of the part. As a general guide, considering costs and lead times tend to be the main factors in making the decision.”

3D printing or CNC machining

Is 3D printing or CNC machining better for prototypes?

AH: “In some cases, yes, unless there are areas within the designed part that are not possible to be produced by a 3D printing method. Although 3D printing is usually a more cost-effective option, there are a few occasions when the machined parts can be more cost effective, so it’s always worth exploring both options. At igus® we would do this anyway to ensure our customers receive the best price and most suitable material along with the best production process for their application and parts.”

DA: “I would argue in most cases, yes. For me, print is quicker, more flexible in our approach and lower cost for low volumes. The exceptions would be where a specific material is required that we can’t print with. Something new is the igus® ‘large scale’ 3D print service where we can now print parts up to 3m long and not far from that in diameter. I’m yet to see that size of stock bar and plate from any supplier in the manufacturing industry, let alone igus. My latest favourite phrase is ‘Think Big – Print Big’. “

What are the benefits of CNC machining custom parts over 3D?

DA: “A larger range of igus® materials can be machined and not printed.”

AH:There are multiple reasons why CNC machining could take preference over 3D printing, such as:

  • More iglidur® materials available to choose from.
  • Higher dimensional accuracy can be achieved and therefore better precision.
  •  Bar stock materials can have their lifetime calculated for application suitability.
  • The bar stock range of products is not size limited and larger sized parts can be produced.

And that is to name just a few benefits of CNC machining over 3D print.”

Applications for 3D printing or CNC machining

What applications for either 3D printing or CNC machining from stock material would benefit the customer rather than moulding?

AH: “Again, there are lots of benefits to choosing CNC machining over moulding which are highlighted in my previous answers. However, the downside is there can be wastage of material when machining the parts. 3D printing has no such waste and moulding produces little waste also.

DA: “Yeah sure, so for small batch production then printing and machining are way more cost- effective than even a simple single cavity tool, but of course, after a certain quantity, that tipping point gets reached. 3D printing has the benefit of taking parts that can be moulded and not machined, and even parts that can’t be moulded or machined and making them a possibility.

What are the 3 top advantages of either 3D printing or CNC machining?

DA: “In regard to 3D printing…..

  1. Complete design fluidity without worry of complex shapes and radius.
  2.  Low cost offerings even for a low volume.
  3. Less waste as it’s an additive manufacturing process rather than reductive.

Something I feel strongly about.”

AH: So let me give you my top 3 for machining then:

  1. Machining from bar stock could be a better option if the material required for specialist applications is not available in 3D print, or if there are special features that cannot be achieved in 3D printing.
  2. Bar stock can be sold directly to the customer, off the shelf within 24 hours, so they can machine in- house and make alterations quicker if required.
  3. The finish of the CNC machined parts can be considerably better if aesthetics is an issue.”

Read what’s new for bar stock at igus here: blog.igus.co.uk/bar-stock-material-whats-new-at-igus/

3D printing or CNC machining? I think it is safe to say that having both options of manufacturing custom parts allows our customers to have the flexibility,  speed and confidence they need to ensure the parts they receive or produce are going to be “plastics for longer life”.

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