Dixons Surgical Instruments is an established high quality medical equipment manufacturer. A change in the complexity of products manufactured has required a fresh approach from the business. Here, Lang 5-axis workholding vices, from Thame Workholding, have supported the transition of the company from hand crafting to precision engineering.
A third generation family-run business, Dixons Surgical Instruments operates from its well-equipped manufacturing facility in Wickford, Essex. Originally established by Managing Director, Jay Dixon’s grandfather in 1948, the company has made some radical changes during the past 5 years. “We have always manufactured traditional surgical instruments, such as rib spreaders, suction tubes and hand held retractors, but in the past 10 years or so we have been moving more towards the manufacture of bespoke orthopaedic instrumentation” explains Jay Dixon.
He continues: “The surgical instruments we have traditionally made are generic and you could buy the same designs from a number of suppliers at a variety of prices and qualities. Today, the traditional surgical instrument market is increasingly opting for products made in low cost economies such as Pakistan. The orthopaedic work is more specialised and much higher precision. The instruments are designed by the client specifically to prepare the bone to accept a particular implant. The success of an orthopaedic procedure has much to do with the accurate placement of the implant, which is controlled by the instrumentation. Orthopaedic companies are not prepared to compromise on the quality of this instrumentation as it has such a bearing on the overall outcome for the patient.”
Having taken over as Managing Director from his father, Jay Dixon says the company has been transitioning from a collective of skilled craftsmen that created traditional surgical instruments, into a focused skilled set of specialised precision medical engineers. He recalls: “In 2010 we invested in CAD/CAM software rather than programming at the machines’ controllers and we have seen the huge advantages of using 3D CAD data throughout our processes. We also bought an EDM wire eroding machine that introduced an exciting new technology to the company.
“Then, in 2013, we bought a CMM that we also program from 3D CAD, using the same solid model for inspection as for machining. The complexity of the orthopaedic work we were doing was increasing and, while we could produce the components using a 4-axis machining centre, we knew there had to be a better way of holding the raw material.”
Most of the components produced by the company are stainless steel, in 17/4PH, 420 Martensitic and 300 Austenitic grades with some titanium, and most are small enough to fit in the palm of your hand. Following a thorough investigation of the various systems available the company invested in the Lang Makro.Grip 5-axis workholding system supplied by Thame Workholding at the beginning of 2014.
“Previously, we would waste an incredible amount of material as the bar stock was held in a 3-jaw chuck on the 4th axis of our Mazak VMC, and had to protrude far enough out so the spindle nose and cutting tool could access it. The Lang 5-axis vices are so compact that the cutter has far better access, and we now only waste a few millimetres of raw material where the clamping points are stamped into the stock,” states Jay Dixon.
Although staff at the company had seen the Lang vices demonstrate their ability to securely clamp parts with minimal raw material holding there was still some scepticism in the workshop when the system was first introduced. As Jay Dixon says: “After stamping, the raw material can be held with a much lower clamping force and the pyramid shaped indents provide accurate datum points so the material can be loaded into the vice without the need for end-stops. Our machinists quickly appreciated the benefits after they had seen it in operation.”
As well as saving raw material one of the major initial gains was using the integrated zero-point interface on the back of the vices to allow the accurate repositioning between Op 1 on the bed of the machining centre, and Op 2 on the 4th axis. “We were limited with what we could do on the 4-axis machine, but the concept behind the Lang system, and the low profile neat vices made us re-evaluate how we could go about making most parts – even the ones we have been making for years, now everything is smaller and tighter,” Jay Dixon says.
To enable the continued growth into more complex orthopaedic work, the company has recently installed a Mazak Variaxis i500 5-axis machining centre. The machine has been specified ready to take the Lang automation system that will feed raw material into the machine and remove the completed parts to allow unmanned machining overnight.
“We already run our EDM machine and vibro finishing equipment overnight,” Jay Dixon explains, “but the intention is to machine parts more efficiently by loading the automation system and letting it run. An average batch for us is 10 to 50 off with typical cycle times between 20 and 90 minutes, so an automation system is an ideal method of meeting the demands of our customers.”
He continues: “The Lang workholding equipment is great value for money, especially when you consider that you can buy the automation ready vices and they are basically the same price as the standard ones. With any other automation system you would also have to factor in the cost of their pallets. With Lang, it’s already built in to the vices. We hope to be ready to run lights-out within the next 6 months or so.”
The concept of using the Lang stamped indents for location has permeated through the company, as the quality department also use them to locate the components when they are being measured on the CMM. The relocation accuracy is stated as 10 micron and the compact nature of the vice allows the CMM probe full access to measure all of the key features of the components.
Jay Dixon concludes: “It is an evolving journey that we have been on, from craftsmen to precision engineers. The Lang equipment has opened up a whole new world for us and the future lies in making better use of technology and to continue moving into more complex orthopaedic work.”
Thame Workholding
Tel: 01844 208050
Fax: 01844 201699
