Trends in drilling and tapping. (Drilling/Tapping).

In the beginning, there were air and hydraulic feed units to perform drilling and tapping operations. Then, with the computer revolution in the 1970s, the first ballscrew-operated feed units came along. More recently, full CNC-controlled feed units were introduced.

Like all technology-driven specialties, each type of feed unit represented a step forward in the evolution of drilling and tapping. Each had something new and better to offer potential users, whether greater productivity, higher performance ranges or less "leadtime."

The advantages of CNC 

In today's increasingly competitive marketplace, drilling and tapping machines must be able to work faster and last longer to meet productivity quotas. Just as important, these machines must be able to deliver consistent results across a wide variety of applications.

Not surprisingly, the leading edge machines in the feed unit arena today are the CNC units with ballscrewactuated quill feeds. What's more, CNC feed units are fast becoming the low-cost alternative to air/hydraulic actuation. "Out-of-the-box," ready-to-run CNC feed and control units can be purchased for under $10,000.

Operators love them because they're so much easier to set up and run. Maintenance loves them because they're so much easier to maintain. Management loves them because they save time and money. And finally, customers love them because they lower part costs. All this love is because of one vital feature--CNC feedback.

CNC feed units have a powerful advantage over air/hydraulic units--they let the operator know exactly what's happening at the tool point. Armed with this knowledge, operators can optimize tool speeds and feeds for maximum productivity.

CNC provides a long list of sought-after performance advantages that make it possible to consistently produce more quality parts per hour at lower cost. They include:

* Less dead time--faster cycle times

* Longer tool life

* Reduced breakage of drills and taps

* Better surface finishes

* More accurate holes

* Better threaded holes

* Greatly reduced maintenance

* Dramatically reduced setup time

* Greater production flexibility

* Ease of programming

* Multi-function capability--rigid tap., drill/tap, and drill/ream

* Single- or dual-axis control

* Fully programmable quill stroke

* Ability to mount multi-spindle drilling/tapping heads

Growing trends

Again, like most technology-driven areas, the cost of CNC feed units is becoming more affordable as more and more of them are put into production. This begets a "spreading out" effect that reaches far more than just the aerospace and automotive industries, which were the first to embrace CNC feed units.

With the cost of CNC feed units approaching that of air and hydraulic units, job shops and die casters can now afford them, especially since the CNC units offer more flexibility, easier setup, less maintenance and the versatility to be reconfigured after the present job is finished.

Still another more recent trend in CNC feed units is the developing evolution from ballscrews to linear motors, which results in even better control and accuracy.

Retrofitting and installation

Another major trend for CNC feed units is in the area of retrofitting older machines. Most production drilling and tapping machines can be retrofitted with CNC feed units, saving their owners a good piece of change while bringing the machines up to current productivity, accuracy and quality standards. Holemaking productivity increases of 50, 100 and 200 percent or more are not uncommon with retrofitted CNC feed units. And programming them to produce families of parts is simply a matter of changing fixtures and loading the new program.

For shops that build their own machines, the CNC controls are remarkably easy to hook up--only a couple of wires connect the control panel to the power source and the feed unit. Zagar will supply customers with the electrical box if needed, but many shops prefer to configure their own cabinets according to the design of their machines.

One of the old arguments against dedicated drilling and tapping machines is what to do with the machine once the job is finished. CNC feed units virtually eliminate that issue from the cost equation. The control panel and feed units are separate modules, so they're much easier to reconfigure for another setup once the part run is over. Many shops consider them as modular tools to be reconfigured many times over for different parts.

Money saving tips

Holemaking consumes a large portion of the cutting time for a typical machining center. This can be a very unproductive use of a high-cost, high-horsepower machine, especially in mid-to-high volume production situations.

When companies are planning major capital expenditures for several multifunction machines that can turn, mill, drill and tap, it may be wise to consider CNC drilling/tapping units in tandem with that purchase. Management may very well find it doesn't need as many multi-function machines after all.

As an example, let's say that requirements for a certain plant called for purchasing five new multi-function machines to perform all the necessary machining operations for a family of parts. A cost-effective alternative to this scenario might be to purchase just three of the expensive multi-function machines, and perhaps one inexpensive CNC feed unit to perform the drilling and tapping functions.

There would be no loss of productivity with this arrangement and the plant would realize very big savings compared to purchasing five new multi-function machines.

This type of application may just become the biggest market of all for CNC feed units as more and more purchasers realize there are available alternative solutions for their requirements. Right now, it's simply a matter of overcoming the mentality of "doing things the same old way."

As more CNC feed units enter production in tandem with machining centers, more and more decision-makers will begin to see the light. And this bodes well for the future of CNC feed unit makers.

Zagar Inc., Cleveland, OH, www.RSLeads.com/110tp-292 or circle 292