Drilling for dollars
- February 26, 2013
by Jim Barnes
Long production time due to deburring holes in aluminum
New drill, end mill tweaks eliminate deburring by 90%, cut part production time by 50%
Tool design improves production operation in aluminum machining
Many small Canadian job shops face huge productivity challenges. The large number of customers they handle and the constantly shifting variety of parts they produce can make integrating high productivity technologies into their processes difficult or impossible.
It is a hyper-competitive business. “Customers wants a part with good value and good finish, but they don’t want to pay extra,” notes Eric Morin, R&D projects director, AMEC Usinage in Saint-Augustin-de-Desmaures, QC.
AMEC, with 54 employees in one facility, is not a large shop. However, notes Morin, “in this region, we are one of the Big Three.” With clients in the energy and transportation markets including aerospace, they run three shifts, with some of the machines running weekends.
The energy market represents about 30 per cent of the business, mostly from parts related to power distribution. Windmill parts, including hydraulic blocks for the brakes on the windmills, are a growing business.
The company’s transportation market includes one big aerospace client. However, notes Morin, they are not currently certifiedto AS9000, which limits the shop’s participation in this market.
Capabilities include machining aluminum, stainless steel, carbon steel, plastics, copper, brass and some work with composites.
Deburring is an issue for many shops that work with aluminum, and AMEC is no exception. Eliminating the need for deburring is a concern for Morin, and he has investigated non-selective technologies like thermal deburring and chemical machining to that end.
However, such technologies “are very hard to integrate in our process, because we are a subcontractor. We are running something like 350 to 500 different jobs a month,” says Morin. The technologies he has investigated are all effective–when you work on only two or three different parts. In that case, he says, “you know the recipe and it’s very efficient… When you are constantly changing all the parameters and geometries, it can be pretty hard to integrate.”
That was why AMEC was receptive when Jean-Sebastien Paquin of Outillage Industriel Quebec Ltd., Quebec City, QC, an industrial tooling and equipment supplier, suggested the company try out Sandvik Coromant’s CoroDrill 860-NM drills. The drills have an unusual cutting profile that dramatically reduces the need for deburring the exit hole when machining aluminum.
The drills were used on two specific projects.
The part involved in the first one was a high powered electrical connector for windmills, made from an extrusion. It is a round tube, about six in. (152 mm) long and three in. (76 mm) dia.
Two holes of approximately 5/8 in. (15.8 mm) dia. were being drilled with a three-axis vertical milling machine. However, there was a problem. There was a “penny”–a circular burr about 1/16 in. (1.6 mm) thick, left after each hole.
“We had to remove that manually, and then de-burr the part” in a second operation, explains Morin.
The new drills did not leave the penny and also reduced requirements for deburring by about 90 per cent.
The solid carbide drill has a new flute shape and cutting edge designed for effective chip clearance, even at higher penetration rates. “With these drills, we are cutting the machining time by about half,” using the same speeds and feeds, says Morin. Increasing speeds and feeds further seems feasible, and the drill offers longer life.
AMEC runs the machine used in this application 20 hours a day, seven days a week. The drills are changed after six months, and getting the additional life out of the tool is a significant cost benefit.
Success in that project led to a second application, also involving an aluminum tube. It was a telescoping aerospace part–an assembly of three tubes that enter inside each other.
The tubes had to be back counterbored, but there was usually a big burr inside the tubes with the previous drills. “Again, we tried the 860 series drills,” says Morin. “We found that there were so few burrs left after drilling that we could do the back counterbore right away, without deburring. It’s a big boost in productivity.”
Combining the new drills with changes to the end mill tooling recommended by the tooling supplier led to a 50 per cent reduction in part production time. It went from approximately 50 min. to 25 min.
The drills required no changes in terms of toolholders or cutting fluids. The tooling supplier walked the programmers and setup people through the tool’s capabilities, which got them up to speed very quickly.
“It was a very simple solution, a small investment that saved us half of the machining time,” says Morin. “That was a good investment!” SMT
Jim Barnes is a contributing editor.