Medical designers have devised many different saw blades, both unpowered and powered reciprocating, oscillating and sagittal types, for surgical procedures. Each one is designed to provide precise, accurate and measurable cuts.
Traditionally these blades are manufactured from stainless steels, the most common being Type 304, the classic 18/8 grade and type 316 with the alloy addition of molybdenum for increased corrosion resistance. However, material selection is becoming ever more critical due to the industry requirement such as corrosion resistance, wear resistance and fatigue strength.
Metal suppliers have developed new and proprietary alloys, incorporating chromium, nickel and molybdenum in order to provide valuable property combinations that offer specific application benefits.
The chromium gives the metal its scratch resistance and corrosion resistance. The nickel provides a smooth and polished finish. The molybdenum gives greater hardness and helps maintain a cutting edge.
Although there are many variations in the alloy recipes, there are fundamentally, two main varieties of stainless steel: martensitic and austenitic. Surgical blades are made out of martensitic steel because it is much harder than austenitic steel and easier to keep sharp.
Blades have previously been fashioned using traditional machining methods, including 3 and 5 axis machining and laser cutting, but in recent times, non-traditional machining techniques have been used to produce these medical incisional parts… namely photochemical etching and Wire Electrical Discharge Machining (Wire EDM).
Photochemical etching is a high precision, controlled corrosion process, which is used to produce complex metal parts with very fine detail.
The photo etching process offers a more cost effective alternative to stamping, punching, laser and waterjet cutting, when machining precision components from thin gauge materials, such as stainless steels, aluminum and ‘corrosion resistant’ advanced engineering alloys.
The use of photo chemical etching in saw blade manufacture has distinct benefits. Shaping, including blade tooth offset and surface marking such as graduation lines, logos and idents can be achieved economically in a single ambient process, avoiding potential heat distortion and work hardening that can be generated in CNC machining. The initial properties of the material remain unchanged throughout the etching process and parts are naturally burr-free, requiring no post-etch processing.
With thicker materials or where parallel sidewalls are essential, wire EDM is the economical solution. Sheets can be stacked for the process, renown for its high levels of accuracy (± 5% of material thickness) and its ability to achieve high levels of surface finish.
As a new and innovative approach to medical saw blade production, currently only a small number of chemical etchers are able to offer this combination of manufacturing capabilities and expertise.
