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The Evolution of Machine Shop Equipment
By Greg Bukosky
Who’s driving this car anyway? That’s the burning question in the engine rebuilding segment of the aftermarket these days. Will advanced OEM engine technology force rebuilders to buy ever-sophisticated (and expensive) rebuilding equipment, or will parts suppliers save the day with new products that don’t require such large investments?
As with most things in today’s world, the answer lies somewhere in the middle.
Without a doubt, OEM advances are changing the way rebuilders ply their trade. As Norm Brandes, owner of Westech Automotive, Silver Lake, WI, said, "Everything that makes a modern engine weigh less, get better fuel economy and last longer has had a trickle down effect on the equipment you find in the shop today."
Cylinder head surfaces
Most aluminum heads now have much smoother Ra surface finish requirements – some as low as 7 Ra. To complicate matters, Chrysler will soon introduce an aluminum block on the 300M with other OEMs sure to follow.
Dave Hagen, technical services manager for the Engine Rebuilders Association, (AERA) echoed the concerns of the industry. "Rebuilders who work primarily on blocks and heads have been very vocal with their concerns about surface requirements. This whole thing has been accelerated by the current trend toward multi-layer steel (MLS) gaskets. MLS technology has been used before in other sealing locations, but just recently for head gaskets. It takes an almost mirror-like finish to properly seal oil, coolant and combustion."
"We recommend that rebuilders check with their gasket manufacturers to see exactly what the requirement is for their application; these numbers tend to vary. To our knowledge, Acura, Chrysler, Ford, Harley-Davidson, Honda, Mazda, Mitsubishi and Toyota are all using MLS head gaskets from the factory. In addition, certain vehicles like the Chrysler 2.0L Neon are being retrofitted with MLS gaskets provided by the aftermarket."
In most cases, the surface finish requirements are a little more lenient from the aftermarket suppliers. Even so, Hagen emphasized that not all traditional machine equipment will be able to provide the proper surface finish for MLS gaskets. In particular, belt sanders and dry stone surfacers cannot get the job done properly.
This new phenomenon has convinced many rebuilders, especially those who specialize in cylinder head work, to actively acquire new equipment with high-tech timers, variable rpm speeds and better surface finishing materials. Shari Goldsberry, manager of Scroggins Machine, Houston, TX, saw the investment as critical to their success.
"We have a great working relationship with the dealer service centers in our area," Goldsberry said. "As we saw more and more aluminum heads come through the shop, it became evident in no uncertain terms that we needed new resurfacing equipment. Fortunately for us, our volume will give us a quick payback on the investment."
Payback seems to be the key for any shop thinking about making a major equipment investment. As one manufacturer pointed out, not every shop will be able to offer full service to its customers like they did 20 years ago. Furthermore, does a market with five machine shops really need five new resurfacing machines? Not if one shop makes the investment and then provides out-service to the other four.
Another new technology that’s having an impact on machine shop equipment is the advent of low tension piston rings. These rings require new honing techniques to attain plateau finishes that are consistently accurate. To achieve this, advances in equipment, abrasives and coolants have all taken place.
Low compression rings were created in the never-ending quest for better fuel economy. What wasn’t initially understood, however, was the effect these rings would have on cylinder wall surface finishes. In the past, a high compression ring would naturally seat itself in the cylinder even when the geometry and finish weren’t exactly perfect. With the low compression rings, this doesn’t happen. To make matters even worse, without a plateau finish, the abrasive cylinder wall scrubs off the thin coating of moly on the low compression ring. The result: the engine passes its initial compression test, but then fails within the first 5,000 miles of the rebuild.
Equipment manufacturers were quick to point out that, unlike with cylinder heads, rebuilders need to achieve exacting Rk values on cylinder walls, as opposed to Ra values. In simple terms, Rk measures the volume of the valleys on a sawtooth finish. To achieve plateau finishes, most equipment manufacturers have added a number of features to their honing machines.
Most notably is the addition of timing features and actual plateau cycles. Older machines have an automatic shut-off function when a certain cylinder size is achieved. Today’s new machines run longer cycles to achieve the desired Rk value. Some machines have gone so far as to add a third cycle for plateau finishing, whereas older machines have only "rough" and "finish" cycles.
Hand-in-hand with new equipment has been the advent of better honing tools. Brushes that have silicon carbide abrasives impregnated into the bristles are one such example. Advances have also been made in diamond honing fixtures as well. Whereas diamonds were once used exclusively for rough finishing, they’re used more and more today for final finishing. This has led to the development of various shapes and sizes of diamonds that break down easier according to the properties of the substrate. Harder diamonds are used for harder metals, softer diamonds for softer metals.
Machine coolants have also come under the watchful eye of equipment manufacturers. Most notably, new water-based coolants are beginning to replace traditional honing oils. The main benefit is that cylinder temperatures during boring/honing are now kept considerably lower, which prevents shrinkage after machining. Naturally, water-based coolants are also environmentally friendly as well.
Last, but not least, a whole new class of surface finish measuring devices has appeared on the market with improved accuracy and ease-of-operation. Prices for these can range from downright affordable to exorbitantly expensive. Rebuilders would be wise to check with their preferred manufacturers to find a product that’s right for their needs – and budget.
This story would be incomplete without a discussion of today’s more demanding tolerances. Because OEMs are making components lighter and smaller, equipment manufacturers have had to create smaller tooling to machine these new components. Some suppliers now offer valve guide tooling as small as 4mm and seat tooling as small as 7/8".
A cylinder head today can have as many as five valves per cylinder with two overhead cams. This creates a real problem for machinists in terms of disassembly and reassembly. A solution provided by one manufacturer has been to create a new valve spring bench which provides a stable platform for removing the retainers and keepers. Along with new keeper tools, work on even the toughest heads has been made quick and trouble-free.
One of the biggest areas of debate for rebuilders in terms of tighter tolerances is the need for high-end valve and seat machines. For high volume, accuracy and repeatability, today’s newer equipment seems to be the way to go. Some rebuilders have reported, however, a need to "kiss" the seats by hand afterward – even when using the best equipment.
Other rebuilders swear by today’s handheld valve seat tools, most of which are fairly high tech themselves. In fact, one equipment manufacturer has come out with a seat cutter kit that allows rebuilders to adjust diameters in very small increments. Rebuilders can also preset the seat counterbore diameter with a combination dial indicator/micrometer to ensure the proper interference fit is achieved every time. Where most rebuilders end up on this subject seems to be largely dictated by personal preference.
When asked to describe the "perfect" piece of equipment, almost every rebuilder we interviewed talked of a multi-purpose piece of equipment that offers quicker set-ups for a wider variety of engines; the less fasteners the better. The need is well warranted given the proliferation of different engine types that machine shops have to deal with these days. To date, several manufacturers have, or are developing just such equipment.
Another area currently being addressed by most equipment manufacturers is the need for better, more flexible finance plans. Financing is generally offered at a five-year term, however, with newer machines lasting longer, some manufacturers are considering 10 and 15 year payment plans.
Most manufacturers (and lending entities) still offer leasing options, although this method seems to be losing some of its luster due to its inherent lack of flexibility in a rapidly changing market. The benefits are that cash flow isn’t affected as dramatically compared to outright purchasing, as well as a host of tax advantages that can boost profits considerably.
The bottom line is that certain types of equipment are becoming too expensive for the typical shop to justify. Most of the equipment manufacturers interviewed for this article agreed that the market will see more niche-type machine shops in the future.
These specialty shops will be complete experts in their field of capability. Even with the machine manufacturers designing more capabilities, speed and flexibility into their equipment, the cost to be a complete, full-service machine shop is simply getting out of reach.
So in what direction should you steer your shop? Some rebuilders, like Leo Croisetiere of R&L Engines, Dover, NH, are cautious to jump on the bandwagon just yet. "Our niche is custom high performance, cylinder heads and restorations," said Croisetiere. "Certainly cylinder heads have narrowed up the playing field. Valve and guide tolerances are more demanding so having the proper equipment and tooling is essential to maintain accuracy and profitability.
"With that said, we’ve looked ahead and decided that we don’t want to be in a position to have to rely on the next generation of engines to survive. It’s not totally an equipment issue, either. The availability of cores due to increased OE controls and preferred partner agreements will make it very difficult from the start. Many smaller shops will find themselves competing toe-to-toe with PERs. I doubt if even the strongest shops will survive playing that game."
Croisetiere went on to add R&L Engines will focus instead on the engines produced in the past 50 years, and agreed, as did others interviewed for this article, that upgrades in equipment can boost efficiency and profits if purchased properly according to a good business plan.
"You don’t just wake up one morning and decide that you need a new boring machine," said Croisetiere. "Equipment acquisition should be an ongoing program with market trends, business growth and obsolescence all factored into the big picture. We plan our purchases one-to-three years in advance so that we can make a profit right out of the box." Sounds like good advice to us.