Process Controls

Solution Analyses

All of our treatment solutions are regularly analysed by our skilled laboratory staff. In a typical week we will do over 50 individual analyses. Based on these analyses we control the concentration, pH etc. of our chemical solutions and this allows us to run our processes with remarkable consistency. We also monitor for contaminants in a number of solutions to preclude regressions in the performance of our coatings.

In-Tank Controls

Our treatment tanks are thermostatically controlled. Where applicable, we also make use of cooling and filtration.

Procedural Controls

All operator controlled variables are controlled by our comprehensive set of procedures. These include variables such as voltage and immersion time. Our procedures are designed to provide the best results for specific materials; we don't take a one size fits all approach.

We produce large numbers of part specific work instructions, which control every aspect of the processing of a given part from jigging right through processing and finally to inspection and packing. These allow us to carefully cater to any special customer requirements or otherwise complex parts.

Neutral Salt Spray Testing

Neutral salt spray testing is a simulated corrosion test. It involves test panels (and sometimes test parts) being put into a test chamber, where they are continuously exposed to a sodium chloride mist for anywhere between 1 hour and 500 hours (our longest test is on sulphuric anodising and is 3 weeks long). After exposure, our technicians examine the test pieces for signs of corrosion, which we evaluate to customer and specification requirements.

This testing provides a tremendous amount of confidence that our treatments not only look high quality in the cosmetic sense, but that they will also function as desired (which you cannot tell just by looking at them).

The amount of time and money that we invest in the testing of "invisible" properties like corrosion resistance is what sets us apart from many of our commercial competitors.

We also offer neutral salt spray testing as a subcontract service. It is included in our Nadcap accreditation and we can offer specifications including ASTM B117 (required by MIL-A-8625).

X-Ray Fluorescence

In 2015 we purchased an XRF to support our zinc-nickel plating process. This allows us to not only measure the thickness of the coating with a high degree of reliability, but also check the composition (balance between alloying elements in the alloy plating). Our XRF is also used for the purpose of identifying the base materials of parts before they are hard anodised if there is some doubt about the declared material.

Coating Mass

Coating mass tests are done to prove that our coating is thick and dense enough. Even for low coating thickness, the coating mass determination provides an accurate and reliable value. Coating thickness is very important when it comes to the functional properties of the coating.

This gravimetric test is performed by carefully dissolving the coating from a test piece and weighing it before and after. We can compare coating mass per unit area with benchmark values in specifications such as MIL-A-8625 or Def Stan 03-18 or we can use it to calculate thickness (depending on the treatment).

We also offer coating mass testing as a subcontract service. It is included in our Nadcap accreditation.

Hull Cell Testing

Hull cell testing is electroplating on a miniature scale. A small sample (about 300mL) of the process solution is placed in a small trapezoidal tank. A set current is applied to a test panel in this solution for a specified period (usually 10 minutes). Once the panel has been plated in the Hull cell, it is examined by a specially trained technician. The trapezoidal shape of the tank causes a current density gradient across the panel, which gives an indication of how the plating solution behaves on even the most complex parts (actual production parts have differing current densities across their surface area based on how they are jigged, their size and their shapes). This allows any potential plating issues to be spotted before they appear on production parts themselves and ensures that our high quality standards can be met all over the part. We made extensive use of Hull cell testing to increase the cosmetic appeal of our zinc plating.

Visual Inspection

Visual inspection is performed throughout processing and all parts are 100% visually inspected at final inspection. Whilst it is rare for components to fail to meet our quality expectations, we want to ensure that the customer never receives anything that is substandard.

Thickness Testing

Coating thickness is crucial to fit and function. We make use of eddy current/magnetic thickness measurement to make sure that we have achieved the requisite thickness. This method is not suitable for certain shapes and areas of parts, so we welcome opportunities to use customer supplied go/no-go gauges.

Electrical Breakdown Testing

Electrical breakdown testing is used on thin anodic coatings (particularly chromic anodising) to verify the film and its dielectric properties.

Why choose Metal Finishings Ltd?

  • Fast turnaround - as short as 24 hours
  • High quality
  • ISO 9001 and AS 9100 certified
  • Nationwide service with our trusted courier
  • No-obligation quotations
  • Free certificates of conformity