Chrome plating is often requested for CNC machined parts that need a specific surface appearance, improved wear resistance, or additional surface protection.
But when you are ordering custom metal parts, simply writing “chrome plated” on a drawing is not always enough.
There are different types of chrome plating, and they serve different purposes. The coating thickness, base material, surface condition, and final dimensions can all affect the result.
For example, a decorative chrome finish on a metal housing has different requirements from hard chrome plating on an industrial shaft.
If you are developing a new component or sourcing CNC machined parts, this guide will help you understand what to specify, what affects the cost, and what to check before placing an order.
1. What Type of Chrome Plating Do Your CNC Parts Need?
Before requesting a quotation, it is worth confirming which type of chrome plating your parts actually need.
The two common categories are decorative chrome plating and hard chrome plating.
Decorative Chrome Plating
Decorative chrome plating is mainly used to give a part a bright, smooth, reflective appearance. It is commonly applied over an intermediate nickel layer, which helps provide corrosion protection and the final appearance.
You may see this finish on:
- Decorative metal housings
- Handles and knobs
- Visible mechanical components
- Consumer product parts
- Metal fittings and accessories
For example, imagine you are manufacturing a custom metal handle for an electronic enclosure. The customer wants a bright, mirror-like surface rather than a matte machined finish.
In this case, decorative chrome plating may be worth considering.
However, the final appearance depends on the preparation of the base surface. Chrome plating will not automatically hide deep scratches, machining marks, or surface defects.
If appearance is important, make sure the required surface condition is agreed upon before production.
Hard Chrome Plating
Hard chrome plating is mainly used for functional purposes, particularly where wear resistance, surface hardness, and dimensional requirements matter.
It is commonly considered for:
- Industrial shafts
- Hydraulic rods
- Cylindrical mechanical components
- Sliding parts
- Certain tooling and machine components
For example, suppose you are ordering a precision steel shaft that moves repeatedly inside a machine assembly.
The shaft may need a hard chrome coating to improve its resistance to surface wear. In this situation, the coating thickness and final shaft diameter become important parts of the manufacturing specification.
Hard chrome plating is not simply a more expensive version of decorative chrome. The two processes have different purposes, coating requirements, and inspection considerations.
Before requesting a quotation, identify whether your priority is appearance or functional performance.
2. What Should You Specify When Ordering Chrome Plated CNC Parts?
One common problem in custom manufacturing is receiving a drawing that says “Chrome Plating” without providing any additional details.
This leaves too many questions unanswered.
A supplier may understand the requested finish, but still need to confirm the coating type, thickness, surface condition, and dimensional requirements before production.
Here are the main details worth including.
Base Material
Start by identifying the material of your part.
Chrome plating is used on different metal substrates, but the preparation process and suitability depend on the material.
For example:
- Carbon steel shafts may be suitable candidates for hard chrome plating.
- Steel fittings may use decorative chrome plating over an intermediate nickel layer.
- Aluminum parts require suitable pretreatment and a verified plating system.
Do not assume that the same plating specification can be applied to every metal.
If your material grade is already specified on the drawing, provide it to the supplier when requesting a quotation.
Chrome Plating Type
Clearly state whether you need decorative chrome plating or hard chrome plating.
This distinction affects the coating structure, performance requirements, production process, and cost.
If you are not sure which one is appropriate, describe how the part will be used.
For example, tell the supplier whether the component is mainly decorative, exposed to repeated friction, or used in a moving mechanical assembly.
Coating Thickness
Coating thickness is one of the most important details for precision components.
A decorative chrome coating is generally thin, while hard chrome coatings are typically thicker and selected according to the application.
The required thickness should be specified on the drawing or agreed upon before production.
For a shaft, even a relatively small coating thickness can affect the final diameter.
If the finished shaft must fit into a bearing or mating component, the supplier needs to know the required final dimension, not just the original machined dimension.
Surface Roughness and Appearance
The required surface condition should also be clear.
For a decorative component, you may need a bright and consistent appearance. For a functional shaft, you may need a specified surface roughness after plating and any subsequent grinding.
For example, if a customer wants a mirror-like finish on a metal housing, the part may require polishing before plating.
If the drawing only specifies chrome plating, the supplier may not know whether a standard finish or a high-gloss appearance is expected.
A reference sample or clearly defined surface finish requirement can help prevent disagreements.
Critical Dimensions and Tolerances
This is particularly important for CNC machined parts.
Consider a shaft with a finished diameter of 20 mm. If the part receives a coating, the coating can increase its outside diameter.
For a coating deposited evenly on both sides, the increase in diameter is approximately twice the coating thickness, assuming the specified thickness is measured on each surface and there is no subsequent material removal.
That means the machining dimension may need to be adjusted before plating.
For precision parts, identify:
- Final outside diameters
- Internal bores
- Threaded features
- Bearing seats
- Mating surfaces
- Areas that must remain uncoated
It is much easier to plan these requirements before machining than to discover a fit problem after finishing.
3. What Affects the Cost of Chrome Plating CNC Parts?
Customers often ask why two parts with similar dimensions can have very different plating costs.
The reason is that plating cost is not determined by size alone.
Several factors influence the quotation.
Part Size and Surface Area
Larger parts generally require more processing resources and may consume more plating materials.
However, surface area is only one part of the calculation.
The shape of the component and the difficulty of processing it also matter.
Chrome-plated aluminum
Part Geometry
A simple cylindrical shaft is usually easier to process than a component with many deep holes, narrow slots, blind cavities, or complex internal features.
For example, a straight steel rod may have relatively straightforward plating requirements.
A machined housing with multiple recessed surfaces may need more careful preparation, masking, and inspection.
Coating Type and Thickness
Decorative and hard chrome plating have different requirements.
Hard chrome plating may involve thicker deposits and additional finishing operations, depending on the application.
If the part requires a specific final diameter or surface roughness, additional grinding or polishing may also be necessary.
These requirements should be considered when comparing quotations.
Surface Preparation
The condition of the machined part before plating can affect the amount of preparation needed.
Parts with visible tool marks, scratches, burrs, or other defects may need additional work.
For decorative chrome plating, surface preparation is especially important because the final coating may highlight defects rather than hide them.
Order Quantity
The number of parts also affects the quotation.
A prototype order of five pieces may have a different unit cost from a production order of 500 pieces.
Some processing and setup costs are shared across a batch, so larger quantities may reduce the cost per part.
When requesting a quotation, always provide the expected order quantity and whether you expect repeat orders.
4. What Should You Check When Choosing a Chrome Plating Supplier?
A low quotation does not always mean you are getting the right finish.
For custom CNC components, the more important question is whether the supplier can consistently meet your drawing requirements.
Here are a few things worth checking.
Can They Meet Your Coating Specifications?
Ask whether the supplier can meet your required coating type, thickness, and applicable quality standards.
If you are ordering hard chrome plated shafts, for example, you should confirm that the supplier can handle the required coating thickness and final dimensional requirements.
Can They Handle Your Part Geometry?
Not every plating supplier is equally experienced with complex machined components.
If your part includes blind holes, narrow recesses, threads, or precision mating surfaces, ask how these features will be handled.
Some areas may require masking or special process planning.
Can They Inspect the Finished Parts?
Ask how coating thickness, dimensions, and surface appearance will be checked.
Depending on your requirements, inspection may include coating thickness measurement, dimensional inspection, visual inspection, and surface roughness measurement.
For critical parts, agree on the inspection requirements before production.
Can They Coordinate with CNC Machining?
This is an important point when sourcing custom parts.
CNC machining and plating should not be treated as completely separate steps.
If the machining supplier understands the final coating requirements, it becomes easier to plan machining allowances, protect critical surfaces, and control the finished dimensions.
This is especially helpful for shafts, fittings, housings, and other parts with tight assembly requirements.
5. What Information Should You Include in a Chrome Plating RFQ?
If you want a useful quotation rather than a long list of clarification questions, provide as much relevant information as possible.
Your RFQ should include:
| Information | What to provide |
|---|---|
| 2D drawing | Dimensions, tolerances, and finishing notes |
| 3D CAD file | Part geometry and manufacturing details |
| Material | Material grade and specification |
| Plating type | Decorative chrome or hard chrome |
| Coating thickness | Required thickness or applicable specification |
| Surface finish | Gloss, roughness, or reference sample |
| Critical dimensions | Finished dimensions after plating |
| Quantity | Prototype, small batch, or production quantity |
| Application | How and where the part will be used |
| Inspection requirements | Required measurements and quality documents |
You do not need to have every technical detail finalized before contacting a supplier.
If you are still deciding between decorative and hard chrome plating, explain the application and performance requirements first.
A manufacturing team can then help identify the information that needs to be confirmed before production.
6. CNC Machining and Chrome Plating for Custom Metal Parts
When ordering chrome plated components, it is important to consider the entire manufacturing process rather than looking at plating alone.
For example, a custom industrial shaft may require:
- CNC turning to produce the required shaft geometry.
- Preparation of the machined surface.
- Chrome plating according to the agreed specification.
- Additional grinding or finishing if required.
- Final dimensional and surface inspection.
If these steps are planned separately without considering the final requirements, problems can occur during assembly.
At Machmaster, we provide custom CNC machining services, including CNC milling and turning, for aluminum, stainless steel, brass, and other commonly machined materials.
We also have an in-house anodizing workshop and can coordinate additional surface finishing requirements through our manufacturing network, depending on the project.
For chrome plated parts, the specific plating process, supplier capability, and inspection requirements should be confirmed before quotation.
Whether you are developing a prototype shaft, ordering custom mechanical fittings, or sourcing production components, we can review your drawings and help assess the manufacturing requirements.
Need a Quote for Custom CNC Machined Parts?
Send us your 2D drawings or 3D CAD files, together with your material, quantity, and surface finishing requirements.
Our team will review your project and get back to you with the next steps.
