|Differences in such things as machine mass, toolchangers, ballscrews and spindles give Hardinge’s three levels of machines their distinct capability and functionality. |
Most machine tool OEMs refer to them as lowend, base, standard, or entry-level models. They are the machine tools that have been scaled back or streamlined to reduce price, but still incorporate the same advanced engineering that goes into high-end machines.
For the most part, standard-model machines differ from their high-end counterparts in terms of capability and functionality.
A machine’s capability involves how well it allows shops to fulfill their particular machining goals, such as producing more parts in a given time period, processing harder materials, or increasing part accuracy and surface finish quality. Functionality, on the other hand, deals more with a machine’s features/options. For example live tooling and a sub-spindle add to a turning machine’s functionality.
According to engineers at Hardinge Inc. (www.hardinge.com), machine tools on the higher end of the scale have more functionality added, and they gain more capability through such things as faster acceleration/deceleration rates, quicker tool changes and better dampening for more precise cuts and surface finishes.
However, shops should only pay for what is truly needed in terms of machine capability and functionality to run their specific array of jobs.
Hardinge recommends that shops keep these basic questions in mind to determine the levels of capability and functionality that are needed in a standard or even a high-end machine tool:
• How many parts need to be produced and at what rate?
• What material is being machined?
• How many operations need to be performed on each machine?
• What surface finishes and tolerances must be maintained?
• How long does a machine need to last and how flexible should it be for future jobs?
The differences between Hardinge’s standard and high-performance milling and turning product lines lie in such factors as machine mass, spindle speed and power, rapid traverse rates, control capability and functionality, and the number of tools or type of toolchanger.
For example, the company’s Bridgeport XV standard-level milling centers typically weigh 9,000 lb to 12,000 lb, while its high-performance XR machines can weigh as much as 29,000 lb. Spindles on the XV machines turn at 8,000 rpm with 20 hp, and those on the XRs turn at 12,000 rpm with 25 hp. XV machines rapid traverse at speeds of 1,180 ipm, while the XRs rapid traverse to 1,692 ipm. The controls on the XVs are basic Fanuc i Series, and the machines include umbrellastyle toolchangers. The XR machines use higher-level Fanuc 18i MB controls and have swing-arm-style automatic toolchangers.
In addition to its standard and high-performance machine lines, Hardinge offers another level of machine tools referred to as performance models. The company developed these midlevel machines specifically for shops that need a bit more capability and functionality than is offered in a standard-model machine, but not as much as in a high-performance one.
|The Mitsui Seiki Vertex high-end, but entry-level, machine |
helps shops transition from 4-axis to 5-axis work.
Because of these mid-level machines, shops do not have to make the jump from a standard machine to a high-performance model just to gain a little more capability and functionality. This also works in the opposite direction for shops with high-end machines that are looking for a somewhat scaled-back model.
According to Hardinge, three machine-performance levels let shops pay only for what they truly need to run specific jobs, as well as allow them to acquire more accurately the amount of capability or functionality they require.
Hardinge’s Standard SV series turning machines have no frills, and are priced to reflect that. The 2-axis machines do not have sub-spindles or live tooling. On the other hand, the company’s mid-level Performance GS machines accommodate the addition of top plates for live tooling and can be equipped with sub-spindles.
“If a customer is interested in our standard model turning machine, but they would really like live tooling, we don’t want to force them to jump to a high-performance machine to get it, which is why we offer mid-level machines,” said Dave Barber, marketing manager at Hardinge.
Scott Walker, president of Mitsui Seiki USA (www.mitsuiseiki.com), agrees that the differences between high-end and low-end machines lie in functionality and capability and that those two factors should match a shop’s type of work. But he adds that shops that purchase high-end machines basically are paying more for tighter tolerances, higher accuracy and machine longevity.
“There is nothing wrong with base-level machines if they are applied to the right kind of job. It’s foolish to buy a $500,000 machine for an $8.00 part, and just as foolish to purchase a $150,000 machine for a $50,000 part. Shops need to match part cost to capital cost,” said Walker.
Consider a shop that’s running a 600-piece automotive brake-drum job and is not sure exactly what type of jobs will be coming through the door next, Walker suggested.
“It would be fool-hardy for such a shop to invest huge amounts of capital in a high-end machine when a standard- type machine would do just fine. The shop then could pick and choose work suited for that machine to pay it off as soon as possible and make enough margin off the machine to perpetuate the shop’s business. This is what makes standard-type machines popular in jobshop environments,” Walker explained.
The opposite side of the coin, he said, would be an OEM shop making integral rotor blades for its own jet engine. That type of work would be considered a core competency, and such a shop would need a machine with high accuracy and longevity.
|The affordable Haas MiniMill gets its accuracy from |
advancements in axis motors and machine motion systems
that have trickled down from high-end machines.
Commonly known for its high-end, super-accurate machines, Mitsui Seiki has ventured into the affordable-machinetools arena with its Vertex 5-axis vertical CNC machining center. However, the company considers the Vertex a high-end, entry-level machine aimed at high-end jobshops that are moving from 4-axis work into 5-axis work for the first time. The machine boasts X, Y and Z-axis resolutions of 0.0000039 in. and A and C-axis resolutions of 0.0001 degrees.
To create affordable lines of machine tools, most builders use basic versions of the same components from their high-end machines and common assemblies and components that transfer from one model to the next. They also limit the amount of standard options available on their lower priced versions.
DMG America Inc. (www.gildemeister.com) uses directdrive spindles on its high-end machines and belt-driven spindles on its new Eco line of turning machines. Both are high-quality spindles, but the belt-driven type is more cost effective. On DMG’s Eco line of turning machines, six live tool positions are standard, while the company’s high-end turning machines offer as many as 12 tooling positions (all live).
The only option DMG offers with the Eco machines is a Siemens control, as opposed to its high-end line choices of Siemens, Heidenhain or Fanuc. Eco machine controls are standard with shopfloor-programming capabilities that allow users to create programs at the machines without having to purchase costly CAM systems. This is especially beneficial for shops that are just starting out and do not have a lot of capital to work with.
“For our high-end machines, we will quote practically anything a shop wants on them. But with the Eco line, the machines are very standard, and not having to build a lot of options into them allows us to produce the machines faster and at a much lower cost,” said Fred Puzon, product sales manager at DMG.
“While they are less expensive, the Eco machines still are built based on our mature product lines and to the same stringent quality requirements as our high-end machines,” he added.
When it comes to affordable machine tools, Haas Automation Inc. (www.haascnc.com) is well recognized. And, according to John Nelson, North American business manager for Haas, there are two main reasons the company is able to offer its machines at low costs.
The first is that Haas buys machine components in large volumes and at less-expensive bulk prices because it sells so many machine tools. Secondly, there is a concerted effort in the company’s engineering department to standardize and use as many similar components as possible across its lines of machine models.
Standardization across machine lines includes using the same ballscrews whenever possible, the same sub-assemblies, and the same controls.
|DMG’s Eco turning machines come very standard, which |
allows the company to offer them at a much lower cost.
For example, lube panel assemblies that encompass lubrication reservoirs, air intake and other components and toolchanger sub-assemblies are used on several machine models. In fact, the toolchanger sub-assembly for the company’s 40-taper vertical machine is basically the same one that goes on some of its horizontal machines. Also, Haas controls are the same across every machine, but they run different software for the company’s turning machines.
One of Haas’s most affordable machines is its standalone Mini Mills (16-in. X and 12-in Y). The fully enclosed machines pack a little less spindle horsepower than the company’s other models and offer several options that can be ordered at the time of purchase or added after the fact in the field. The field-added options include fourth-axis rotary tables, high-flow coolant pumps, probing systems and chip-auger systems.
Haas recommends getting machine options at the time of purchase to save on service labor charges, but Nelson said that the more common scenario is that many start-up shops don’t have the capital to spend on options at that time, so they wait until they’ve been in business a while then purchase the field-added options.
As far as affordable high-tech is concerned, Nelson said that improvements in technologies such as positioning accuracy from high-resolution encoders and better axis motor performance have, over the years, made their way from high-end machines to affordable models, giving them quite comparable accuracies.