A few pointers about the factors that affect a moulderâs output, including machine precision, tool quality and workpiece control.
Moulding can have a significant impact on the final look of many kinds of custom woodwork. There are many options available to woodworkers when choosing a moulder to produce them. How does a woodworker go about choosing the best moulder for his shop? CWB contacted several moulder manufacturers to help carve out the answer.
Q. What are the key factors in moulder setup and operation to achieve a superior surface finish?
A. Peter Riehle, president, Michael Weinig Inc.: Precision in the manufacturing of each moulder component is the key. All of the individual parts must come together precisely in order to achieve a superior surface finish.
The other factors are the cutterhead and knives that are used during the process. Proper balance and design must be taken into consideration for the different material species and feed rates. Then, holding the product so the moulder can produce the finish is the final task.
Naturally, the material does not want to stay in place while it is being fed into a cutter. In this case, special pressure elements â like our cassette pressure shoe system â are required to accomplish this. This process can be automated at various levels to help the operator change quickly from one profile to the next.
A. Jon Morris, director of marketing and communications, Woodstream Moulders and Mereen-Johnson: We focus on three key factors:
First: Tool quality, including sharpness, concentricity and balance. While the sharpness of tooling is often overlooked, it is critical for best moulding quality. It is important to note that tools should not be left to dwell in cut during setup. Dwelling the tool quickly overheats the cutting edges and eliminates sharpness.
Also, good concentricity and balance are needed to minimize vibrations. Often, a good tool can be thrown off-center by minute amounts of wood dust or small wood fibers being trapped under the tool mounting surfaces during a tool change. This is particularly important with HSK-type tool mounts, with higher RPM, which are prone to vibration problems if not kept perfectly clean.
Second: Machine alignments, including table and fences. Often the fences and table plates close to the cut, which are adjusted frequently, are not always kept level. This will always cause surface problems.
Third: Close control of the wood through correct pressures and guides. We have been working hard at Woodstream to make all guides easier to set, without the complexities of motorized axis and computers. All important fences, chipbreakers and pressure assemblies should be adjusted and set correctly according to the stock removal, tool extension and finish profile produced by each tool.
A. Chuck Carter, technical team leader, Solid Wood Technologies, Stiles Machinery Inc.: Provided the moulder is supported with good quality tooling, the next most overlooked adjustment that directly affects finish quality is control, or lack of it. Not controlling the work piece as it is being machined can introduce chatter and/or heavy undesirable knife marks.
Controlling the work piece can be associated with several different areas within a moulder. If we look at a common spindle shaper, it features adjustable fences that can be adjusted as close to the toolâs cutting diameter as possible. By reducing the distance between fence plates, better work piece control is gained, as the uncontrolled or unsupported distance the work piece must travel is minimized. The finish quality with moulder fences, bed plates, and chipbreaker and pad shoes can be increased dramatically if they are adjusted properly.
Another important area is the type of pressure loading supported by the chipbreakers and pad shoes. Spring pressure is the most common with smaller machines, but it requires the operator to compress and decompress the springâs tension from one setup to another. A wider work piece may require several pounds of spring pressure, while narrow parts require hardly any. Most operators do not make the needed adjustments, as they are time consuming. So they often struggle between good finish quality and work piece feeding issues.
The best alternative is pneumatic loading with an external regulator adjustment. Pneumatics are most often found on high-speed moulders, as they react faster than springs. On custom short-run applications, it provides the operator the ability to dial in just the right amount of pressure quickly.
The most common control issue today is normally associated with the pad shoe on the last top position. Alignment issues and lack of surface area hold-down are the major issues here. A misaligned shoe can promote poor finish issues, as the shoe should always be parallel with the bed plate underneath it. Additionally, the amount of contact area the pad shoe has with the work piece is also considered. Shapely moulding may require controlling it at different heights. Special hold-down shoes are available that will allow contact with the work piece at multiple levels to gain control. Custom shoes can be made to mirror the work piece contours to provide maximum work piece control.
A. Tom Milldall, technical support manager, Leadermac USA: Users should purchase a moulder to fit all of their production needs, paying attention to feed speeds, spindle tolerance and how impervious the moulder is to dust and moisture.
Users should also ensure that the moulder is balanced and precision-ground to pattern or insert tooling. Well trained operators are also key.
Accurately ground hard chromed bed and pressure plates, an excellent feed system utilizing many bed and top powered rolls, and pressure control hold-downs make it simple to achieve a perfect finish quality.
Q. What is the most important requirement to ensure consistent stock feed?
Riehle: The machine must be accurately aligned during the manufacturing process. The operator must use the proper pressure elements to ensure that the applied pressure on the material does not cause the material to stop feeding.
Quality feed rollers are key to maintain a continuous, constant positive feed. Quality of the rough lumber (bow) must be in a certain range to avoid too much tension that will stop a moulder from feeding.
Having an automatic feeder to feed the material into the moulder instead of feeding it by hand eliminates gaps between pieces and ensures a reliable and safe feeding process.
Morris: Assuming the machine is correctly aligned and control pressures are correctly set, moulders generally require the right balance between sufficient down pressure of feedrolls to penetrate the stock, but not too much pressure and bed friction to stop the machine from feeding.
More table rolls reduce bed friction, and advanced feedrolls with inbuilt depth limitation provide consistent feed with less down pressure.
Carter: Many things contribute to ensuring consistent stock feeding. Proper tooling, spindle RPMs, computer setting aids and other features sold today on modern moulders are useless if the machine cannot feed work pieces consistently. End users note machine design changes within the last decade, where we see the trend to build lighter weight moulders to reduce cost and promote smaller footprints. The disadvantage is a light-weight feeding system that struggles on rough material. In some circumstances, the number of feed rollers throughout the moulder have been reduced as much as 30%.
The older standard of using double outfeed rollers to pull the work pieces out of the machine have now been replaced with a single roller. A single outfeed roller will often struggle to pull work pieces out of the last machine positions, especially when heavy cuts are being made. We also see a reduction in the number of bed rollers used in todayâs moulders. The more bed rollers within a machine, the better thru-feeding ability it will have. The width of the bed roller is also important, as it should always be as wide as the work piece it is feeding.
Today, more moulders are offered with chrome beds and fences. The coefficient of friction of chrome vs. the standard steel bed plate is much less. Therefore, we find bed lubrication, which was needed to extend bed plate wear and promote work piece feeding, is almost non-existent today when chrome beds are used.
Other simple considerations are the sharpness of the feed rollers. Typical feed rollers will dull within the first 1-1/2 years of use and must be serviced. Feed rollers turning on stationary work pieces can dull dramatically within a short time frame. All feed rollers must maintain a common height above the table so that all provide feeding benefits.
Feed roller pressures are also important, as most should maintain 40 to 50 psi of pressure. We commonly find feeding systems operating above 60 psi to compensate for dull rollers. This can damage the overall feed system if not corrected. Many times, the condition of the lumber and the type of wood species can overcome the simple adjustments and require extra measures that are dependent on the situation.
Milldall: Consistent stock feed can be achieved through more bed table rolls, as well as the pneumatic control of key pressure points and heavy-duty feed.
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