Bowtech Products was established 22 years ago as an importer of products used for underwater applications, but now designs and manufactures its own equipment. Exports currently account for two-thirds of turnover, which has helped to double the size of the business over the last five years and was one of the reasons for the company winning the Subsea UK Global Export Award 2012, sponsored by Scottish Enterprise.
Manufacture of components has historically been subcontracted but is gradually being brought in-house to control costs and quality as well as to shorten lead times from weeks to days. Two CNC lathes and a machining centre from Hurco underpin this activity at Bowtech's production facility on the Kirkhill Industrial Estate in Dyce, near Aberdeen airport.
Typical batch size is 100-off, which is now more economically produced on-site, while small runs and prototypes are machined much less expensively than when they were put out to external machinists. Cameras and LED lights are core Bowtech products, particularly those mounted on remotely operated underwater vehicles. Business is so brisk at present that, so far, efforts to reduce subcontracted manufacture have been thwarted, as internal manufacturing capacity has been consumed by growth in demand. So Bowtech has decided to build a new, dedicated machine shop which will become operational in 2013.
Meanwhile, the Kirkhill unit continues to lead the way within the group in bringing machining in-house. The main activity of the division is production of polyurethane joints that connect submerged electric cables. Manufacture of injection mould tools to make the joints is the province of a Hurco VM1 vertical machining centre, installed in 2009.
Stuart Rowley, Cable & Mechanical Moulding Manager at Bowtech, said, "After I have designed the two halves of a tool, production takes two to three days on the Hurco, whereas lead time was much longer when we had the mould made outside.
"Before we bought the VM1, we looked at a similar machine in operation making mould tools at the Great Yarmouth factory of SEACON (Europe), whose underwater electrical connectors we sell in Scotland. "We realised that the WinMax software in the Hurco control was ideal for small quantity mould production, due to the powerful conversational programming capabilities. It takes next to no time to master.
"To maximise its effectiveness, we bought the manufacturer's 3D Mold package and practically every other software option."
The success of this first in-house machining venture encouraged Mr Rowley in 2010 to consider making camera and light housings on site, which need a lot of drilled and tapped holes on the ends of round components. The Hurco TMM10 CNC turning machine with 10-inch chuck and driven tooling was the obvious choice, as it is controlled by Windows software that is so similar to the milling version that Bowtech staff did not even need to go for the training that came with the lathe purchase.
Most recently, a Hurco TMX8MY lathe has been added. Of 8-inch chuck capacity, the machine has a Y-axis to allow off-centre cross-drilling of holes and milling of flats, functions that are not possible on the TMM10 machine.
The company tends to pick higher added value work to turn-mill in quantities of up to 100-off. Larger runs, which can be as high as 1,000-off, continue to be subcontracted for the time being. Materials range from anodised aluminium through stainless steel to titanium alloy for the high value end of Bowtech's product range. Accuracies held are typically 0.125 mm total, although some O-ring grooves need to machined to a tolerance of 0.025 mm.
Mr Rowley opted to install Hurco's off-line WinMax programming software on his PC. It arrived ahead of the VM1 and at the outset was a useful facility for self-training. Now it is used to review the next program off-line while a part is being machined on the machining centre or one of the lathes. This approach allows the progression of a live program to be monitored at the machine controls, instead of tying it up programming the next cycle in background.
Mr Rowley continued, "If more complex cutter paths are needed for any particular routine, such as engraving our company logo into the curved surface of an injection mould, we use AutoCAD Inventor to create the design and output it as a DXF file that the WinMax control is able to read directly.
"The big advantage of Hurco's NC Merge capability is that we can program conversationally around the DXF element to generate the complete cycle, without having to use tedious G and M codes. It is surprising how easy it is to do."
A probable next step for Bowtech will be to consider 5-axis machining to address milling of complex titanium components, which have to be machined from the solid, as casting are very costly. Such work also tends to be expensive if put out to subcontract.