Q. How much stock can I remove in one pass?
A. Stock removal on a widebelt sander is determined more by the abrasive belt than by the machine. Each abrasive belt is designed to remove a certain amount of stock, and if that amount is surpassed, the life of the belt is affected. As a rule, you will need to use the lower grit belts for heavy stock removal (36-80 grit belts can remove approximately 1/8 inch to 1/32 inch respectively) and medium grit belts for lighter stock removal (100-120 grit belts can remove approximately 1/32 inch to 1/64 inch respectively). Belts in grits from 150 on up should only be used for finishing and are not considered cutting belts. Other factors affecting stock removal are: abrasive belt speed, type of sanding head, feed speed and available horsepower.
Q. What are hold-down shoes, and when do I need them?
A. Hold-down shoes in a widebelt sander are similar to chip-breaker shoes in a planer. They are used to control the part as it passes through the machine, prevent dubbed or sniped lead and trailing edges, and to allow for shorter parts to be run. Specific uses are: short parts, narrow parts, parts under 1/4 inch thick, veneered panels, or any time you need to hold close tolerances.
Q. What is a segmented platen?
A. When sanding veneered panels or sealer/lacquer, utmost control is required. To accomplish this, the platen (or shoe) is made up of individual segments which receive sanding pressure individually (pneumatically or electronically). These segments are controlled by a CNC controller that, along with a sensing unit, can be programmed to activate only when needed. By doing this, you have the ability to conform to the irregularities of the panel and sand without the fear of sanding through the sealer or veneer.
Q. How many sanding heads do I need?
A. This depends on your production needs and the end finish required. If your production will not allow for multiple passes, a two- or three-head machine may give you the required finish in one pass as opposed to two or three. As mentioned earlier, abrasive belts can only remove a certain amount of stock dependent on grit size. With a three-head sander you can run a grit sequence of 100-150-180 and remove approximately 1/32 inch in one pass. To determine how many heads you require, you need to know how much stock you need to remove and what is your final grit finish. From there you work backwards to determine how many heads are needed. (Remember, you should not skip more than one grit size in a sequence).
Q. Should we sand with a drum or a platen?
A. Generally speaking, a drum is used for stock removal and a platen is used for finish sanding; however, drums are also used for finish sanding in some applications. A rule of thumb would be that, if you need to remove more than 0.003 to 0.004 inch, you should use a drum, otherwise a platen may be used. The difference between the two is also seen in the finish. A drum will produce a short scratch pattern, but it is deeper on a given grit. A platen will produce a longer scratch that is not as deep. You really need to determine stock removal requirements and desired finish to decide which will fit your individual needs.
Q. What is sealer sanding?
A. Sealer (lacquer) is the first coating applied to your product after finish sanding or staining. The purpose of this is to fill in or "seal" the wood pores and protect the wood. A negative effect to applying sealer is that, being a liquid, it raises the grain of the wood, producing a rough surface. Sealer sanding is performed to create a flat, smooth surface with the proper texture, so that the next coat (also known as the top coat) will adhere properly. Methods used for sealer sanding are: hand sanding, widebelt sanding, brush sanders (both hand held and feed through), and with feed through orbital sanders.
Answers about Widebelts courtesy Timesavers Inc.
