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Improve dimensional control, reduce cycle time and increase production efficiency
By Al Choiniere, COO of Superion, an Allied Machine & Engineering company
Combining operations in a single tool is a significant trend sweeping through the metal cutting industry. Combining cutting operations reduces the cost per hole by eliminating tool changes. It improves production efficiency and machine utilization, ultimately increasing manufacturers’ speed to market. 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 worthwhile. Plus, combined step tools can be factory reconditioned, making combining cutting operations an extremely cost-effective proposition.
It all comes down to production efficiency and reducing cycle time
Efficient machine utilization affects a company’s ability to get its products to market quicker – and speed to market has a major effect on the bottom line. Machines are expensive and labor costs are even more so, so utilizing those expensive machines to the maximum is the name of the game. This can be done by combining operations in one cutting tool.
Most shops have one operator to run 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 this set up time, contributing to the cycle time reduction. It also lessens the amount of perishable tooling inventory. In addition, combining operations on one tool controls hole dimensions, forms, and shapes. It gives users the ability to hold critical tolerances, improving dimensional control, and hence production consistency.
Who benefits from combined operations?
Typically, high production contractual/production shops doing repetitive work would benefit most from combined operations. Smaller job shops that only do a few pieces or run prototyping jobs would not gain as much from combined tool operations. Typically a company would use multiple standard tools to prototype a part to demonstrate their capability of making the part. During production, they would look to switching over to a tool that can do as many operations as possible.
Modern manufacturing shops primarily use 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.
For example, 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 when needing to produce a hole with a top and bottom chamfer. The CNC tool can be used to drill and chamfer the top hole and then circular interpolate the chamfer or edge break on the back of the hole – all with one tool.
Another advantage of step tools is for forming complex forms, such as cavity ports that have multiple angles running into radii. The end user can control all tolerances in the tool and would not have to program the complex information into several tools to complete that same difficult form. This means it will result in higher accuracy and faster production, while also maintaining consistency, especially in complex forms.
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.
Unique tools support raw materials advancement.
Many new tools are being developed to support recent advancements in raw materials, especially for aerospace and automobile applications. For example, aircraft are being manufactured with lightweight, extremely strong materials, such as carbon fiber reinforced polymer (CFRP) and carbon fiber reinforced thermoplastic (CFRTP), which 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.
Many are looking for PCD step tools that 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.
Solving hard metal tooling customer challenges with step tools
Here are two interesting examples of real customers who benefitted from combining operations into a step tool.
The first is a defense company making small arms. The chamber in the barrel featured multiple angles, radii, and diameters. The typical tool design would not allow all the operations to be done in one step. This left a significant amount of hand work for a gunsmith, who had to make the chamber smooth enough so the bullet would not drag across it and cause jamming. We combined the tooling to completely eliminate the gunsmith work, removing the human element and guaranteeing a smooth chamber. What’s more, the combined tooling saved on production time, while also reducing the potential for liability in case of firearm malfunctioning.
This second example is an even better illustration of why combining step tools can be such a game changer. In this case, we worked with a growing business that was manufacturing aluminum automotive parts. The company already had four CNC machines running three shifts a day to keep up with their workload. Then their biggest customer informed them they would be adding more work – requiring the part manufacturer to triple its production!
The plant manager had to come up with a feasible way to ramp up production by a factor of three. He was initially looking at a building expansion and adding more machines, but was concerned about the time lag this would cause. The company approached Superion and asked how quickly we could add more tools to accommodate the increase. The company was using solid carbide tools with step tools. After reviewing the operations, I explained that if they switched to diamond tipped step tools they could increase production, and meet customer demand without a building expansion.
Rather than adding eight more machines and adding on to their building, they only had to bring in one more machine – period. Not only did this save the customer millions, it also improved part consistency and quality without increasing tooling costs over a three-year period. The part manufacturer was able to tell its customer they could be ready for the ramp-up within two months rather than the several more it would have taken to add building square footage and machines. They had the room to add another machine, and were also able to reduce the number of shifts, which opened up additional capacity so they could take on more work.
Combining operations makes the most from CNC advancements
The advancement of CNC machine tools is one of the most significant developments in metal cutting.Now we have to create cutting tools that can take full advantage of CNC machine capabilities. At the same time, the raw materials to make cutting tools has also improved, with a shift to new materials that increase tool life, cut cleaner, and last longer, including PCD, cubic boron nitride (CBN), ceramic, and cermets.
In the past, the perceived high cost of tools for combining operations led people to shy away from doing so, thinking it will be more expensive than standard off-the-shelf tools. In actuality, manufacturers will gain far more with cycle time savings achieved on the production shop floor. In addition, these step tools can be sent back for factory reconditioning to new or nearly new condition, depending on tolerances, multiple times. This further reduces expenses, making the option of combining tools even more appealing.