KICK UP THE VOLUME

When machining geometrically defined edges on intricately shaped parts, broaching uses a multiple-edged tool to make straight cutting movements. The broaching process has traditionally been considered economical only when used to process large batches.

There was a recent impression – it lasted only awhile – that some of the surface broaching operations were going away, but not the internal splines or features that are done on the inside of a hole. That school of thought said these could be done on a CNC machine tool and a company wouldn't have to buy a broach just to do one operation. You'd take the part, put it in a CNC machine and it would do every operation, including what was previously broached.  Many thought broaching OEMs were losing some of that market share. However, these machined features have been coming back to broaches due to the relatively high production quantities you can achieve with a broach as compared with a CNC machining center. You can make the same quantity on a broach that it might take ten machining centers to produce.

Though the range of applications vary, typical one-ton capacity broaching machines can offer an 18 in stroke, 50 ton machines have 72 in strokes, and there are used machines up to 75 tons with 110 in strokes that are used to broach large internal gears for wind-powered turbine generators.

This provides broachers with certain opportunities in market sectors that really need their help. For example, given all the problems in the domestic automotive industry right now, the auto companies are doing more final assembly work and producing fewer component parts themselves because they're buying those from first tier suppliers like American Axle, Delphi, and others. This causes those Tier One companies to tool up, meaning Tier One and at least two automotive suppliers are buying and investing more in equipment, in effect making these companies a growing customer base.

First tier companies are also farming out some of their part production to even lower tiers, allowing some broachers to weather the downturn in the automotive business over the last three to five years. Because of the used machine side of the broaching business, broachers are able to serve these lower tier customers. They may no longer be making half million or million piece production rates, but they are still making a hundred thousand parts – and they still need to broach it.

For many machined products, broaching remains the fastest and often most accurate way to machine certain features. Today 80 to 85 percent of broaching remains automotive related, with the remainder used in off-highway, heavy machinery, earth-moving equipment, arms manufacturing, hand tools, aerospace, alternative energy, and even the medical industry where parts for hip, elbow and knee replacements are broached.

Splines and keyways are just two part features that are best done by the broaching process. Other methods either can't cut them or are comparatively too slow or expensive. Broaching machines are typically dedicated to high volume production and are often engineering-intensive, which makes them relatively expensive compared to other machining methods.  However, there are few faster metal removal processes in the world today. 

What should a company consider when looking at buying a new or rebuilt machine? Typically it's driven by the budget, which is usually dictated by production requirements.

For example, Bob at XYZ Machining Company might be making 50,000 parts per year and buy a used horizontal broach for $20,000 or $30,000 tooled up. His volume makes it more economical for him to broach the part internally with a used machine rather than farming it out. However, if Bob attempted to purchase a new $250,000 machine, he couldn't afford it and wouldn't be getting into the broaching business. So the bottom line is the bottom line: his decision is driven by his budget.

The opportunity doesn't stop there, however, because Bob at XYZ Machining Company might be making 50,000 pieces of the same exact part that maybe American Axle or Delphi is making in quantities of 500,000. Delphi and American Axle can afford that brand new, automated machining system, but the guy making 50,000 parts probably can't. This means the opportunity for broaching OEMs exists on both sides of the equation. OEMs are uniquely suited to serve both levels of business.

When a broaching machine is rebuilt, the only thing that's really "old" on the machine is the iron base (either a casting or weldment), which comprises the frame and slides. Everything else is either new or completely remanufactured. The mechanical portions are re-ground and re-fitted to new machine specifications. The electronic controls are all updated to the latest programmable logic controller (PLC) controls and hydraulic systems are retrofitted with the latest components. A broaching machine should not be remanufactured with any component that is no longer available nor supported, and the machine buyer should have the same warranty that a new machine offers.

New broaching machines are most often prepared as turnkey systems and designed to be robust and durable for long service life with minimal maintenance. These turnkey systems usually include ancillary equipment that the OEM holds to the same standards of reliability as its own equipment. Ancillary equipment can include filtration systems, material handling and chip removal systems.

One of these pieces of equipment that is vital to the broaching process is a high-volume magnetic chip conveyor, such as those built by Storch Magnetics (Livonia, MI). There is a unique requirement for chip removal with broaching machines because they accumulate a lot of chips and remove vast amounts of metal. There are a number of different ways to do this.

In the days prior to magnetic technology, this was primarily done with a simple drag-type conveyor. But today, the primary materials being broached are ferrous in nature and magnetic. This makes a magnetic chip conveyor the logical way to take the chips out of the chip collection sump in a safe and efficient manner with an extended service life. Magnetic removal allows the liquid coolant to flow back into the machine and provides the advantage of being able to filter or separate out some of the fine shavings that would otherwise be floating in there. The magnets draw the shavings and chips onto the conveyor and then take them out. 

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Matt Egrin is the president of Broaching Machine Specialties Co. (BMS), 25180 Seeley Road, Novi, MI 48375-2044, 248-471-4500, Fax: 248-471-0745, www.broachingmachine.com.