Besides the material processing, the decisive characteristic for the quality of a screw clamp is the continuously high clamping force together with the long service life of the product. In the case of screw clamps of low quality, endurance tests have shown that the clamping force can already decrease significantly after only a few working operations.
Pay attention when purchasing clamps
To maintain the pressing force in the long term, the following points should be observed when purchasing clamps: In both malleable cast iron and all-steel screw clamps, a movable pressure plate, a solidly fixed handle and a smooth-running spindle are important. In addition, trapezoidal thread spindles with a relatively large pitch are advantageous, as they enable fast adjustment and efficient force generation at low torque. In the case of malleable cast iron screw clamps, care should also be taken to ensure that the castings are accurate, burr-free and stable. A straight, finely ribbed rail also ensures that the sliding arm is easy to adjust. With an all-steel screw clamp, the high quality of the hardened and tempered material is also visible.
Proper care and cleaning
To maintain the good quality of a screw clamp in the long-term, proper care is essential. The function of a screw clamp is based on the friction and tilting between rail and sliding arm. It is important, therefore, that the rail is always kept free of grease, oil or dried glue. Particularly critical on the rail are waxes and release agents containing silicone. Such residues must be removed as quickly as possible using solvents, wire brushes or sandpaper. Both the spindle and the pressure plate joint should be lubricated regularly with a little oil. Spray oil is especially suitable for this purpose. In this way, the smooth running of the screw clamp is maintained for a long time with optimum clamping force.
If there is a grub screw on a malleable cast iron screw clamp, which prevents the sliding arm from slipping through, it can be readjusted by a quarter turn when the support starts to diminish.
With all-steel screw clamps, attention should be paid to any shine forming on the rail, as this can lead to slipping of the sliding yoke. If shiny spots are visible, they can be roughened on both sides with emery cloth in grain size 100 to ensure safe working again.
Well stored, quickly found
Different throat depths and clamping widths of the screw clamps can cause problems during storage. A practical solution for this is a clamp trolley. Because this sturdy metal construction with rollers can hold the clamps sorted by size. In addition, a mobile clamp trolley enables more flexible and faster working, as all clamps are always at hand and clearly sorted directly at the point of use. A further storage option is a stationary shelving unit where the clamps are simply pushed onto it.
Anyone who already pays attention to high-quality screw clamps at the time of purchase, regularly maintains them, and cleans and stores them properly will enjoy their clamping tools for a long time to come – if not even from one generation to the next.