Keyways and splines are slots used to transmit mechanical forces in a wide variety of mechanical parts in all engineering disciplines. Because broaching internal keyways and splines typically accounts for only 1% to 2% of all work performed on a machined part, not many companies invest in dedicated machines to perform this type of work. It is therefore a highly specialided niche market and remains an engineering discipline that hardly any one likes to do.
Keyways and splines are generally manufactured through broaching, slotting, milling, EDM or wire cutting. Each method has its own restrictions, particularly in the length they can achieve. Misalignment, deflection, vibration and size limitations are common problems faced by engineering workshops using conventional methods to cut keyways or splines in long parts.
However, one Queensland-based company is providing a solution, promising a fast and reliable turnaround, cost effective production, tight tolerances and a high quality finish in difficult parts, with keyways up to 700mm long. Elmass (Australia) discovered this niche market 18 years ago and has been manufacturing precision keyways and splines for a wide range of industries across Queensland and Australia using its patented broaching tools and machines.
Starting its operation using specialised tools on a pedestal drill, Elmass has evolved into a highly specialised broaching workshop operating four CNC-controlled broaching machines in Northern Brisbane. The company is capable of broaching up to 700mm long internal keyways or up to 500mm long splines, hexagons and other shapes. As the only company in Australia utilising the Belgian-manufactured Elmass broaching machines, it currently services a wide range of industries including mining, agriculture, hydraulics and general engineering throughout the country.
Across its four easily-programmable CNC-controlled broaching machines, the company is able to broach keyways and splines to suit any application. The P36-700 three-axis machine can broach keyways up to 36mm wide and 700mm long, and splines up to 500mm long, in blind or through bores. The P36 has a usable machine frame height of 1,400mm. This allows it to accommodate very long shafts that require a blind keyway or spline. Recently a 5mm wide and 75mm long keyway was broached in a 1150mm long shaft, using a 100mm long tool bar. There was plenty of room left to operate the machine comfortably. For another company a 38-tooth DIN spline was broached in a 654 long shaft using a similar set up.
On the opposite end, the fast and efficient P10-200 machine can broach 2mm-10mm keyways and splines in small parts up to 200mm long, and is highly suitable for mass-production.
Elmass’s exceptional precision and capabilities can be attributed to a number of factors in its manufacturing process. The hydraulically-driven toolbars are guided at the point of cutting. Therefore they cannot deflect or vibrate during broaching, resulting in accurate keyways that meet tight tolerances. The flexibility regarding the bore size, keyway size and keyway length is due to the interchangeable toolbars, cutters and guide bushes which can be assembled to meet individual job specifications. Furthermore, the Elmass machines are equipped with interchangeable mounting chucks and adjustable turntables, to fit the length of the part. Custom toolbars, cutters and guide bushes can also be created in a short time-frame to meet any specific product requirements.
The eccentric guide bushes are self-centring. This ensures that the keyway or spline is always perpendicular to the bore and maintains the depth of the cut over the entire length of the bore. These machining characteristics of the guided tools facilitate the broaching of 10mm wide and 400mm long keyways in JS9 tolerance in quills for the oil and gas industry that have a bore size of only Ø38mm.
The distinctive design of the cutters allows them to be resharpened on a surface grinder without losing their tolerance. Additionally the shape of cutters can be designed to deburr the tooth in the final broaching strokes, which reduces the overall production time of the part. The final product is a precise, high-quality keyway or spline without the drawbacks or limitations of traditional broaching or manufacturing methods.
Elmass offers a priority breakdown service where the required machine can be booked in advance. The machine will be set up during the time the part is in transit. Once received, the part is often broached while the customer is waiting. This service is essential for time-critical repairs in mining and manufacturing where a breakdown can cost a company tens of thousands of dollars per the hour in lost production. The company also designs and makes guide bushes and cutters to meet any non-standard application within a few days.