Aerospace surface treatments are often priced on a job by job basis, and can vary greatly from job to job.
Coating Type and Process Chemistry
The cost of the process itself is typically the largest variable when it comes to pricing for surface treatments. For processes like hard chrome and electroless nickel, the tightly controlled bath chemistry and process parameters along with the need for skilled and trained process personnel to apply the coating, all contribute to higher costs. The consumables and specialised equipment used for thermal spray processes also typically add to the cost of these processes. Simple processes like anodizing are typically less expensive, while very high performance coatings, such as HVOF tungsten carbide, are typically the most expensive.
Part Geometry and Masking
More complex parts are typically more difficult to process and therefore cost more. Parts that only require certain areas to be coated require these areas to be masked before processing and unmasked after processing. Labour to properly mask parts with blind holes, threads, or small internal cavities is very expensive and generally considered to be a large portion of the coating cost.
Pre-Treatment Requirements
There are normally several processes required before coating can be applied to an aerospace component. These processes are grit blasting, degreasing and chemical etching. Some components arrive at our facility with heavy contamination, others may arrive with signs of corrosion and in some cases they may already have a coating applied. If this is the case then the component will require stripping before any other process can take place and this will cost. Also, the cost for preparing a component for coating will decrease if the component arrives at our facility in a clean and prepared state.
Batch Size and Setup Charges
Setup charges: the cost of setting up a process to coat parts. This will include filling up a tank, building a jig to hold the parts, checking the process etc. It will cost the same to set up a process to coat a single part as it will to coat twenty parts. Where possible it is wise to group parts together in batches to reduce the unit cost.
Certification and Specification Costs
Aerospace surface treatments must be conducted using documented process standards for the aerospace industry. Suppliers of aerospace surface treatments have significant audit and approval costs associated with the aerospace industry standards and accreditation requirements. First-article inspection, material test reports, and approved process certification add to the cost of the process, especially on low volume production parts. Aerospace Surface Treatments is covered in more detail at www.poeton.co.uk/about/industries/aerospace-defence/.
Knowing which of these variables apply to your parts will give you a better basis for comparison of cost between suppliers and for planning of your expenditure.