First Published on FDMC | September 16th 2016
By Dennis S. Walsh
Are you getting maximum performance out of your widebelt sander for all the different tasks you need it to do? Conducting a professional evaluation of the wide sanding belts used in a cabinetmaking operation can offer valuable insight, including:
While shop personnel can do basic evaluations themselves, Norton Abrasives’ application engineers are available to cabinet manufacturers to conduct professional evaluations of the widebelts in use to achieve correct thickness and finish on cabinetry components.
The reasons for conducting such evaluations vary. Perhaps a cabinetmaker wants to assess the operation with an eye toward maximizing quality and performance. The manufacturer may be considering changing belt suppliers, and want to evaluate competing products. Or the cabinet manufacturer might want to qualify a belt for use in a particular task. In this account, the assumed purpose is a comparison of belts currently used to alternatives of another kind or from another supplier.
Three story boards are used by Norton application engineers for a professional evaluation of wide belt sanding. The boards are made from ¾-inch MDF and are 4 inches wide and 8 feet long.
The first step after the decision to conduct a widebelt evaluation is for a Norton site manager to meet with or call the appropriate plant person and review the steps Norton requires for conducting a widebelt evaluation. This ensures that there are no delays, misconceptions or confusion when the Norton engineer arrives on site to supervise the evaluation.
Once a test date is confirmed, the plant must create three story boards (4-inch by 8-foot medium- or high-density fiberboard test boards, ¾-inch thick). Also, plant personnel must select cabinetry components to be used in later stain tests.
Running story boards
The story boards should be run before or when the Norton engineer arrives on site. Typically, the story boards can be run on a Friday before the beginning of an evaluation on the following Monday. They should be run through the sander selected for the evaluation, and the sander should be outfitted with new belts of the type presently used in the operation.
The following steps must be followed when running story boards prior to a widebelt evaluation:
- Measure each story board at four places along its length to ensure its uniform thickness.
- On the sander, measure from the front of the first head to the outer side of the last head to ensure that the story boards are long enough to be partially sanded by all heads during a partial pass through the machine.
- Log the machine’s digital (target thickness) setting.
- Conduct a start-up check that includes locking out the machine, removing the sanding belts, blowing out the machine and the dust vents then closing the dust vents, inspecting dust hoods for debris and rollers and platen for damage or excessive wear, and installing new belts before opening the dust vents. The machine is now ready to have the lockout removed and the belts jogged to check tracking prior to running it.
- With the sander running, set the target thickness.
- Feed the story boards into the machine simultaneously, one each four to six inches from the conveyor belt edges and one in the center of the conveyor.
- When the leading ends of the boards exit the last head, stop the conveyor and shut off each head.
- Open the machine about an inch and remove the story boards.
- Note which story board was at which location on the belt and measure each board before and after the stop point for each head.
- Compare each board’s thickness following sanding by the last head to the machine setting.
- If the measurements indicate that the machine is not calibrated correctly, advise the appropriate person so that adjustments can be made before the arrival of the engineer who will conduct the belt evaluation.
Performing stain tests
To evaluate widebelt sanding performance for stained components, some 30 sample components are sanded on test belts for a compatibility study.
Before the wide-belt evaluation, a stain test is performed on cabinetry components to be run on the test belts. These tests are performed to ensure that the finish on components sanded on the test belts matches the finish produced by the belts currently used and also meets the plant’s color and adhesion standards.
To perform this test, Norton engineers employ belts of the kind currently used and sand at least one component for each relevant stain color. If the standard finishing process for the components includes wide orbital sanding, that, too, is done before staining. Then, the stains are applied followed by the standard finishing process: sealing, loose fiber removal and clear finishing. These finished parts serve as controls in the evaluation to be performed on alternative belts.
Next, the test belts are installed on the sander and the same sanding and staining process is performed on at least two parts for each stain color.
If the stain test shows that the finish produced using the test belts meets plant standards, then 30 components are sanded on the test belts for a compatibility study. Before and after sanding, thickness measurements are taken on diagonally opposite corners of each panel.
When evaluating widebelts, Norton application engineers typically spend a week in a plant. Central to this process is maintaining a thorough log of belt changes and the regular checking of workpiece thicknesses.
A belt-change log sheet, which is provided to the sander operator before the evaluation begins, provides spaces for recording each belt change including the date and time each belt was put on and removed, the reason for the change and the operator’s name. The operator must record belt changes on the log because this information provides the basis for the evaluation of the new belts and comparisons with the performance of the previously used belts.
The operator or the abrasive supplier’s applications engineer will check workpiece thickness once an hour and record the results for the comparison of stock removal versus the specifications.
At the end of a week of testing and measuring, it will be clear to the abrasive supplier’s engineer as well as personnel in the cabinetmaker’s shop whether changing to a new abrasive in a particular wide belt application will improve the manufacturer’s performance or productivity.
See the full Evaluating Wide Sanding Belts article on FDMC