What is the Trimming Process and How is it Performed?
Trimming is a process used to remove excess material to achieve a desired shape, size, and finish, while removing burrs and smooths out sharp edges. To trim a part, it is put on a lathe and processed by a highly skilled metal spinner, or a trim machine, and a cutter is used to shear or shave off the edge so that it runs true. A trimmed edge may either be a straight off trim, radiused or beveled, ensuring the edge is safe for handling. The tool utilized is called an insert, or a cutter, and are designed for applying the correct trim. Though there are a variety of tools to be used, the metal spinner is trained to know which is ideal for the part requirements.
Did You Know Skilled Metal Spinners Trim?
Did you know that in some circumstances, a part will be spun to be close enough to a certain dimension, and the metal spinner will manually perform a final trim to achieve the desired dimension with very high accuracy. A skilled metal spinning can trim an edge to be within 1/64th of an inch by their sight and feel. Dependent on the part configuration, the part will be checked with a Vernier caliper, micrometer, pi taped band, and even a tape measure to ensure the part is within the specified tolerance. Skilled spinners work within +/- 0.005” depending on the part configuration and material used, impressive!
Why Trim Metal Parts?
Removing burrs and softening sharp edges is important for a finished part to be safe to handle, and it gives it a nice, clean edge, as it may not have right away. For example, deep drawn parts such as cups or domes are always trimmed, as there is oftentimes excess material around the edge from the forming process. Trimming allows for a uniformly shaped piece while also allowing for a visually appealing product. Smooth and clean edges are much more aesthetically pleasing than a rough edge.
Preparing for Further Processing
Trimming may be a necessary step to further form the part. For example, in order for a flange to be added on a cylinder, or a beaded edge, to a lid, the part needs to be trimmed first to ensure that the added form is the right size, free from burrs and excess material so that the final form functions properly.