by Al Choiniere
Combining cutting operations in a single tool increases speed to market
Machines are expensive and labour costs even more so. Utilizing shop equipment and staff to the maximum is the name of the game and one way is to combine operations into one cutting tool to reduce the cost per hole by eliminating tool changes. It improves production efficiency and machine utilization, reduces cycle time, and ultimately increases manufacturers’ speed to market.
High production, contractual production shops doing repetitive work would benefit most from tools that combine operations. Typically, a company would use multiple standard tools to prototype the requested part to demonstrate their capabilities. Once the customer reviewed the sample part and signed the contract, the shop would invest in a single tool capable of performing all the required operations for the job.
Most shops have one operator running multiple machines. The more tools used to perform an operation, the more setup time is required. Using one tool instead of three or four reduces set up time, which helps reduce overall cycle time. It also lessens the amount of tooling inventory. In addition, combining operations gives users the ability to hold critical tolerances, improving dimensional control, and hence production consistency.
Modern manufacturing shops use primarily CNC machines; combining operations means they can use one tool to drill, chamfer, back chamfer, and even mill. This is much better than using a machine that can only perform one in and out movement. Combining operations in a CNC machine may facilitate circular interpolation, in which a rotating tool can follow along a circular arc. This can be a huge advantage in drilling bores with O-ring grooves. The CNC tool can be used to go in and out and also perform the circular motion needed to form what is required. By using CNC technology, operators could drill to open the hole, circular interpolate with an end mill feature, and then chamfer to break the sharp edges–all with one tool.
Step tools are also good for creating complex forms, including cavity ports with multiple angles running into radii. The machinist can control all tolerances with a single tool and does not have to program complex information for several tools in order to complete that same difficult form. This results in higher accuracy and faster production, while also maintaining consistency.
One key example is SAE and/or ISO hydraulic ports, which feature forms with multiple angles and radii that all need to be controlled within each other. This combination of critical features makes them difficult to produce without a step tool. With combined tools, the port can be drilled from solid to a finished port all in one shot. This can be a significant time saver. All CNC machines use tool changers, and moving from one tool to the next may take as much as 10-30 seconds of cycle time. Remember, in production shops, every second counts.
Many new tools are being developed to support recent advancements in raw materials, like carbon fiber reinforced polymer (CFRP) and carbon fiber reinforced thermoplastic (CFRTP). While lightweight and strong, these materials are extremely abrasive and hard to machine. Machining with carbide tools is possible, but the tools wear out very quickly. This has led to the development of tools made with polycrystalline diamond (PCD), a superhard material with many advantages over tungsten carbide alone. PCD step tools can combine rough operations with finishing operations, so operators can drill, mill, and ream with one tool. The combined PCD tools are also being used in the automotive industry for abrasive high silicon aluminums.
The only thing preventing many manufacturers from combining operations is the perception that step tools are far more expensive than standard tooling. In fact, the cycle time savings alone makes it a worthwhile investment. SMT
Al Choiniere is COO of Superion, an Allied Machine & Engineering& Engineering company