The wide-belt sander is one of the most common pieces of equipment used by manufacturers to calibrate rough dimensional material to a standard thickness and condition a wood surface to receive one or more coatings. However, many wide-belt sanders are improperly operated.
Each use of the machine is specific and for it to function correctly, the operating parameters need to be adjusted to match the expected task. Neglecting crucial steps in setup, operation and maintenance can result in substandard finishing results on sanded surfaces, higher labour costs due to extra repair or rework, and increased belts costs due to higher-than-normal sanding belt use.
The sanding process is the step that prepares and improves the surface of the wood to receive further processing or finishing.
Wide-belt sanders come in many different configurations. In general, the addition of more sanding heads to a machine translates into fewer changeovers required to achieve the final objective. Unfortunately, be- cause of incorrect setup, most sanding heads remove more than the required amount of material. By obtaining knowledge on sanding theory, on the machine’s physical abilities, and on how to test and set-up the wide-belt sander, operators can achieve improved sanding results. Removing the right amount of material and establishing the level of the sanding heads is as important as using the appropriate type of abrasive material.
Maximizing the performance of a wide-belt sander involves focusing on a few key points. These include the machine, the abrasive, the application, and the dust extraction system.
The Machine
The starting point for improving the machine’s performance begins with its setup. Operators need to consider the configuration of the machine, the condition of the sanding drums/ platen and feed belt, the level of the sanding heads and the setup of the shoes and rollers. Operators also need to know the operating speeds of the sanding heads and feed belt. In addition, the operators must be aware of the minimum width and length of material the machine can handle; whether a change of sanding grit is required, as well as the direction of the calibrating mechanism, so that all adjustments can be made in the closing direction. The operation of a wide-belt sander should be based on fact. Load meters, gauges, or the practice of removing pencil lines are not recommended ways to indicate how the machine is performing.
The Abrasive
Abrasives play the main role in material removal and in conditioning the product before the next step. Some factors to consider when using abrasives are: how the abrasives have been stored prior to and between use; if the abrasive is the right choice for the application (grit, backing, type); the speed that the abrasive is run at; if the abrasive is used evenly and correctly; and the scratch depth and pattern. Remember that the abrasive does all the work; the machine is just the vessel for the work.
The Application
Manufacturers use wide-belt sanders in a variety of applications to achieve a desired outcome. To help attain a consistent end result, the establishment of standardized practices takes into account such variables as the starting and ending parameters, the sanding sequence for material removal, the flatness of the piece on the first pass, and whether the entire width of the sander is being used. Other aspects to consider are the type of wood species being machined and if it contains cross-grain; the thickness variance between pieces; the time between sanding and finishing, and if there is a need for subsequent hand sanding.
The Dust Extraction System
Dust extraction plays a very important function in the operation of a wide- belt sander – improper dust extraction greatly affects the performance and life of a sanding belt. Dust that is carried or adheres to the belt will lead to poor sanding results. As dust builds up be- tween the sand paper granules, the heat that is produced results in the dust particles becoming hard. Poor cutting and streaking is often indicative of poor dust removal. A rough guide to deter- mine if the amount of dust extraction is adequate is to observe how much dust is accumulated and how frequently the dust within the interior of the machine needs to be cleaned out. With many items to consider in the operation of a wide-belt sander, a little education can provide the opportunity for better performance and cost reductions during the sanding process. When an operator con- siders the depth of scratch, removal amount, feed speed, grit sequence and wood species, the proper processes can be put in place to achieve the required result. Paying attention to these factors will go a long way in getting the most out of the machine and achieving the finish that your customers will surely appreciate. For more information on this topic, contact Brian Ehrecke.
Brian Ehrecke is an industry advisor for FPInnovations’ Wood Products Division who provides technical and manufacturing support to the cabinet and millwork industry. He can be reached at (250) 462-4000, or brian.ehrecke@fpinnovations.ca FPInnovations is a Canadian non-profit organization with more than 25 years of experience providing technical support to the wood products industry in Canada.
Reference:
• Sanding Systems Consulting Inc., Howard Grivna
