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The challenge of improving product quality and turnaround times in the demanding area of orthopedic implant and instrument manufacture has been solved for one British company by ANCA.
Corin Group, one of the world’s leading orthopedic implant manufacturers and a renowned innovator in this field, has recently installed the ANCA TX7+ CNC grinder to machine bone rasps, which are used during the surgical implantation of hip replacement devices. It will also be used to grind knee implants, which surgeons use to treat patients with severe osteoarthritis of the knee.
Corin Medical was founded in 1985, based in Cirencester in the heart of the Cotswolds in south-west England. The company was named after Corinium, the early name for Cirencester, a historic Roman town mentioned in scripts as far back as 150 AD, and now known as “the capital of the Cotswolds.”
Corin Group is committed to providing effective techniques that restore mobility and relieve the pain of osteoarthritis and is particularly focused on providing innovative solutions for restoring quality of life for younger, active patients. Latest generation surgical instruments, together with minimally invasive systems and surgical navigation, support a wide range of orthopedic implants.
With increasing demand for their products from across the world, Corin decided that they had a need for a five-axis CNC grinding machine. After discussing their requirements with several companies, Corin asked Coventry-based ANCA UK to provide a solution for grinding rasps, and machining femoral components for their knee systems, with a view to providing a significant reduction in their current cycle times. The solution was the ANCA TX7+ machine with UGS NXCAM for post-processing output and Cimulator3D for verification.
Steve Bass and Andy Morris from ANCA UK completed two comprehensive demonstrations and showed that the ANCA solution delivered the customer requirements in terms of size tolerance, quality, surface finish and a reduction in cycle time. Corin had previously used a milling operation to produce the rasps with a cycle time of four hours per part. Using the ANCA TX7+ the cycle time was reduced to under an hour with a far superior surface finish.
Corin Operations Manager Richard Hemming explains the effect the TX7+ has had on their production.
“The ANCA machine has reduced our cycle times significantly compared with previous methods and allowed us to reduce our lead times to days from weeks.
“The quality and the surface finish on the bone rasp is excellent, with greater consistency than from previous methods.
“We placed the order with ANCA because the cost, delivery lead time and technical support package all met our requirements. The TX7+ machine has allowed Corin to increase our flexibility and productivity and we can now respond to customer requirements within a matter of days.”
Generating the program in UGS NX CAM took approximately two hours for the rasp shown in the picture on page 22. The time required is largely dependent on the number of teeth and the contour shape. There were 48 teeth to grind which required individual sheet bodies to be modeled to ensure that wheel position and depth would be correct all the way around the contour profile. The model of the fixture was also required to ensure wheel collision would be avoided as the wheel approached this section of the rasp.
ANCA has created several different post-processors that convert the 3D model into a program usable on the ANCA machine. Which one is to be used will depend upon the part geometry. For the most complex parts, a five-axis post can be used, taking advantage of all CNC axes on the TX7+. For the Corin bone rasp, a 2D polar post was used that controls only the Y- and A-axes.
An important enhancement that has been recently added to these posts is the Cutter Radius Compensation (CRC) function.
Previously if there was any change to the grinding wheel dimension, due to wear for example, the whole model had to be put through the post-processor again to generate a new program. The CRC function can now compensate for wheel wear by performing an automatic update to the program.
ANCA is confident that the TX7+ machine will be the first of many at Corin, which will assist growth and help the company to develop their range of orthopedic implants further into the worldwide medical market.
About ANCA
ANCA was founded in 1974 to design and manufacture high technology computer numerical controls (CNCs) for the machine tool and metal-based industries. Today, ANCA has become a leading designer and manufacturer of complete, CNC high-precision grinding machines in a global niche market. With its core values of precision, innovation, quality and technological excellence, ANCA is today an international organisation of more than 350 employees with a robust set of technological and entrepreneurial skills. Offices are located in major cities in Europe, North America, South America and Asia; with dealerships represented in over 25 countries. ANCA continues to understand market demands and produce products and services to benefit its customers.
ANCA has experienced an average annual growth rate of 30% and is aiming to set new production and sales records for 2006/07. Over the past six years, ANCA has sold $500 million in exports for Australia and is number one in the US, UK and Asia-Pacific markets for CNC high-precision grinding machines. Approximately 7% of ANCA’s revenue is ploughed-back into development of new technologies. In the past 12 month period, $6 million has been re-invested in the Bayswater plant in new equipment to ensure the company stays at the leading edge of production efficiency and product quality.