The artistry of plating

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The artistry of plating

21st Jun 2022
by Edward Moss

What is plating?

Plating is a very common finish used for machined components. It is a surface covering process where a thin layer of metal is added after machining. There are many different forms of plating or coating including various types of anodising, chromate and non-chromate conversion, chrome plating and electro-polish. Benefits of plating include decorative qualities, improved corrosion resistance and increased durability.
 

Why is plating a specialist process?

Soft sulfuric blue anodized support bracketWhat is often overlooked is that plating is very different to CNC machining. It requires extensive craftsmanship skills and the careful management of multiple variables and control factors. It is not a computer-controlled precision engineered process – it is almost artisanal.

The end results are affected by the following factors:

  • The grade and source of the component’s raw material
  • The geometric shape of the component
  • How the component is held, supported, and fixed through the plating process
  • Where the item is positioned within the processing vessel
  • How the component is orientated throughout the process
  • The other components that are processed within the same batch
  • The skill and experience of the individual performing the process
  • The industries and market sectors usually served by a processing company along with the type and nature of the work they regularly perform
  • The unit price per item you are willing to pay for the process.

The tighter the post-plating finish tolerance or the more aesthetically perfect the desired result, the more care, time, control and therefore cost is involved. For example, the consistently beautiful, brushed aluminium finishes on Apple products are no accident, they have invested millions in developing the production process.

How to accommodate plating at design stage

If your plated or coated components have finished sizes with less than 50 microns total tolerance range, or if you are producing a customer facing component where aesthetics are important, here are some of the main considerations:

  • Cerakorte coated aluminium 6082 T6 enclosure lidThink about plating process requirements during the draft design stage. Engage with a competent plating company or a one-stop machining service provider to understand any potential processing issues and gain agreement on how to plan for consistent plating in the design
  • State on the drawing if the finish sizes are pre or post plating
  • Larger parts being electro-plated may need two dedicated blind tapped holes at either end of the component to guarantee a good electrical connection and remove any opportunity for arcing and damage
  • For plated or coated components, only specify tight tolerances if necessary
  • Discuss plating allowances (growth per face in the plating process), both with the plating company and the machinist. Include processing notes on the drawing
  • As tolerances become tighter, there is a need to process components in their own individual batch and not mixed with other dissimilar parts
  • Where tolerances are critical, post plating grinding and honing may be required to guarantee consistent results. 
  • Unless necessary, don’t specify threads with class fits. There are multiple tolerances interacting when a screw and nut are assembled
  • If the aesthetic finish is important, include notes on the drawing and:
    • Carefully select a plating company to partner with who typically processes that type of work
    • Discuss directly with the plating company how the part will be processed. Can it be jigged on hidden features? You may need to consider dedicated blind tapped fixture holds

Choose a one-stop shop to benefit from expert advice on machining design and finishing processes

Natural hard anodised 7075 T6 structural aluminium side support platePartnering with a one-stop shop such as Penta will give you access to extensive support on finishing processes, and machining design advice. For time-poor buyers, entrusting the whole machining and finishing process to one supplier could help you save time and money. 

At Penta, we work with a network of carefully selected plating and coating suppliers. All parts are subject to our rigorous quality procedures and go through a full inspection before being dispatched, ensuring we deliver outstanding quality finished components time after time.

Get expert help from Penta Precision

"Penta Precision produced two polished acrylic mould prototypes for us, which needed to fit together seamlessly. Penta produced the mould to the exact size and within the time that we needed. I will definitely use them again for future projects." Matt - Design Manager

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