Secure vacuum clamping for CNC foot insoles

Busch Seco rotary vane vacuum pump.
Busch Seco rotary vane vacuum pump.

In addition to a podiatric clinic, Koordynacja also develops and markets orthopaedic devices. The latest development is a CNC milling centre, which reads patients’ data and automatically manufactures orthopaedic insoles from foam material with the required dimensions and density. During the milling process, the foam material is clamped securely to the machining table by vacuum. Mariusz Strzecha, the proprietor of Koordynacja and developer of the milling centre, chose a Busch Seco rotary vane vacuum pump for the vacuum supply. Numerous trials with other vacuum generators were conducted, but only the Seco system met all the requirements for series production.

Koordynacja was founded in 2010, and initially specialised in podiatric orthopaedics for athletes. Strzecha used the experience acquired in this field to develop new diagnostic devices, which he now manufactures and markets with the help of his employees. The patients attending his clinic benefit from the latest diagnostic equipment. Strzecha is convinced that at some point in their lives, most people experience back or joint problems caused by misaligned or asymmetrical feet or different leg lengths. These problems could be avoided by compensating for foot and leg discrepancies using custom-made orthopaedic insoles.

Insoles during the milling process.The foam material is clamped to the machining table by vacuum.

Strzecha uses a number of diagnostic devices in his clinic: patients’ feet are 2D scanned, photographed, casts are made in foam, and pressure points are identified by the patient walking on a pressure platform or treadmill fitted with pressure sensors. The alignment of knees and hips are also measured, and finally a 3D scan of feet is conducted. Information gathered from these examinations is entered using a special software package developed by the company. The software calculates the perfect shape of the insole required, and passes the data to the CNC milling centre.

The CNC milling centre ‘CNC Foot Insole’ was developed in 2014, and is sold across the Poland, but soon the market will spread to neighbour countries. In Poland, Koordynacja works with orthopaedic specialists who make their own diagnosis, take measurements, and send data for the insole to be produced by Koordynacja.

Pump performance  

Before the insole is milled, the most suitable foam material must be selected. Koordynacja uses a variety of materials comprising layers of different hardness, allowing a perfect match to the patient’s requirements to be made. A block of the chosen foam material is placed on the machining table of the milling centre, and is clamped securely using vacuum applied through channels in the table by a Busch Seco rotary vane vacuum pump. The vacuum pump must apply sufficient force to prevent the material from moving.

For Strzecha, it was important to find a vacuum pump with adequate performance reserves that operated quietly, reliably and without oil. After a number of experiments with other vacuum generators, he found that the Busch Seco rotary vane vacuum pump provided the perfect solution. These pumps work without operating fluids, which means they use no oil and maintenance tasks such as oil and filter replacement are not required. The compact dimensions of the vacuum system allow it to be installed in the housing of the milling centre. The pump also runs very quietly, and is inaudible above the noise of milling operations.

Vacuum pump output was an important issue for Strzecha: all the layers of foam used for the insoles are permeable to air to some extent, so a certain amount of leakage is experienced during the milling process. The Seco vacuum pump has a pumping speed of 5 m3/h, providing sufficient reserves to evacuate through the foam material without loss of vacuum level and subsequent reduction in clamping force. The high throughput also reduces the time taken to conduct the clamping operation.