Wednesday, February 11, 2009
CAD/CAM Foot Orthoses: CNC technology
Foot orthoses come in different types from simple insoles to biomechanically calculated platforms to help stabilise the foot during phases of walking. In recent years there has been a sizable industry grown around the manufacture and prescription of the latter which is now estimated at $30 million US per anum. Prescribed foot orthoses often referred to as function foot orthoses are used by sports specialists, surgeons, physiotherapists and podiatrists and prices vary from $20 to $300 per pair depending on the type, time spend and materials used. Over the counter foot orthoses are often as effective as bespoke varieties but due to the material combinations may not always last quite so long. Conditions definitely apply. For over a decade the manufacture of foot orthoses has involved Computer Numerical Controlled(CNC) systems where CAD/CAM software programs are used to produce a computer file that is interpreted to extract the commands needed to operate a particular machine, and then loaded into the CNC machines for production which involes a complex series of steps needed to produce in this case a foot orthoses. CAD software produces 3D scanned design data which can be manipulated to add a range of models, add-ons and cut-outs or corrections to the foot mould. Many companies which supply bespoke foot orthoses use the technology to increase their production. The established method of producing bespoke foot orthoses was both time consuming and prone to human error. After physical examination of the leg and foot, technicians took plaster of Paris moulds of the feet set in a reference position. These negative casts are then filled with setting plaster before drying at hot temperatures. When the foot models are completely dried high temperature plastics are melted over the prepared cast before trimming. The process of creating unique prescriptions for patients suffering from various foot and joint ailments will take anything from 3 days to three weeks to complete. A primary advantage of CAD/CAM manufacture is the time reduced in producing quality foot orthoses as providing prescribed quality foot orthoses in a timely fashion translates well to high profits. Turnaround time is extremely important in the bespoke foot orthotic business. Delcam's OrthoModel , is a new software specifically for modelling and machining custom foot orthoses. Once the information is input into the OrthoModel CAD software, the information is transfered to the CAM component OrthoMill and routed to complete the milling process. Top covers and other finishes are added once the foot orthoses have been milled. Delcam Crispin is a UK based company founded in 1965 and their software includes a series of menus which incorporate the biomechanical terminology used by the industry to describe the various features of the foot orthosis.