Mathison Engineering, a family-run sub-contract machining business, specialises in producing 316 stainless-steel marine fittings in quantities ranging from one-off prototypes to high-volume runs. Accounting for around 80% of the company’s turnover, these products are to be found in vessels all over the world — but mainly around the coasts of Europe, the USA and Iceland.

Winning a contract earlier this year to produce components for super-yachts meant that a new vibratory bowl was needed to clean, deburr and finish the surfaces of larger components, as the existing machine at the company’s Gosport factory was too small. The parts are mainly for concealed hinges and latch-type locks used in applications ranging from deck hatches to diving platforms.

Steve Mathison, who runs the company together with parents John and Sarah and four additional staff, spotted the PDJ Vibro stand at the MACH 2014 show in April. The following month, after successful trials at the supplier’s Milton Keynes technical centre (www.pdjvibro.co.uk), an EVP-A 220 vibratory bowl was installed at Gosport. The improvement in the standard of finishing has been significant.

The 240-litre capacity PDJ Vibro bowl features continuously recirculating water, automatic dosing of detergent, an acoustic cover for noise suppression, and a screen to allow parts to be easily separated from the finishing media, which are also supplied by the same company.

Furthermore, the machine can shut down all services automatically to allow ‘ghost shift’ running for a predetermined duration — normally 4hr, which is sufficient time to process a batch of stainless-steel parts. It is no longer necessary to run the bowl continuously all evening and overnight until the start of the next morning’s shift, as with Mathison’s smaller machine; this wasted power and was rarely the optimum processing time.

Mr Mathison said: “The PDJ Vibro bowl is much more productive. We can easily finish 400 components in an 8hr shift; and with the separator screen, they are much quicker to extract. Our operators particularly like the semi-automatic separation. They are delighted that the days of plunging their hands into a mixture of cold water and abrasive and sifting the parts manually are over.

“Typically, our components are ready for shipping to the customer a week earlier than before, and the finish is much better. Not only are components cleaner due to the continuous flow of water, but the abrasive action is more efficient as well. It results in effective edge deburring and an improved finish on the surfaces, so machining marks are no longer visible.”

A polished finish

The latter advantage, achieved using porcelain stones in the bowl, can be augmented by exchanging them with a ceramic medium to achieve polished surfaces. Mathison Engineering gains significant financial advantage this way, as any components that need an even higher cosmetic finish, requiring them to be sent out to a polishing specialist, are now processed in less time and at a lower cost by the third party.

Moreover, Mathison’s use of the PDJ Vibro equipment ensures that components do not lose shape due to aggressive linishing to remove cutter marks.

Overall, the surface quality and the appearance of components are much improved, which is just what many marine applications call for — Mr Mathison says that super-yacht owners can be unbelievably fussy about the look of their fitments.

A recent development of Mathison’s is the polishing of white plastic components — such as mounting blocks for hinge arms — in a 2hr cycle. It was impossible to process these parts in the old vibratory bowl, so the ‘as machined’ finish had to suffice.

The customer can now choose the option of a smooth shiny finish; this is not only more attractive but also enhances the functionality of the block, which acts as a bearing surface.

In addition to machining all grades of stainless steel and plastic, Mathison regularly produces components for the telecommunications industry as well as the aerospace, rail and food sectors.

Materials range from aluminium and brass to mild steel and titanium. Another benefit of the new vibratory bowl is that all of these metals can be processed using the same abrasive medium; with the previous bowl, it was necessary to exchange the stones to tackle different materials.

In conclusion, Mr Mathison said: “PDJ Vibro was by far the best at responding to our enquiry at MACH and following it up afterwards. We also like the fact that they are a family-run business — like ours — prepared to do that bit extra for the customer.”