To provide the high-performance results demanded in today’s moldmaking, many indexable-insert ballnose endmills use PVD-coated, precision-ground, micrograin- carbide inserts. Experience shows that such inserts perform best with sharp edges, which represents a departure from the conventional wisdom that extra-strong edges are required to stand up to hardened materials at very high feedrates. […]
Within this decade, advanced carbide cutting tools used with constant-chip-load CNC cutting strategies have dramatically increased material-removal rates in roughing of mold cores and cavities. The combination of these tools and strategies also results in dimensions closer to near-net shape, which favorably impacts subsequent finishing operations. As impressive as these roughing approaches have been, however, [...]
Both solid-carbide and small indexable-insert ballnose endmills are capable of the speeds and feeds required for high-speed finishing of molds. Moldmakers should keep in mind, however, that the indexable-insert tools offer important cost advantages – starting with a much lower replacement cost and no regrinding. […]
Checking for Positive DraftOn occasion tool marks can be so deep that they reduce the draft or the polisher accidentally takes off the draft. The key is to always check for positive draft by putting a six-inch scale on the wall and comparing the angle it makes to the parting line. It takes just a [...]
If we consider the primary metal of steel, which is iron, there are a number of features that we can observe immediately about the metal: […]
Of all the tasks polishers face in the moldmaking trade, texture and its related problems are probably among the most challenging. Getting hand texturing to match up perfectly with acid bath texturing is a skill entirely unto itself, but with a few tricks of the trade, almost any polisher will be able to stand up [...]
Many industries place strict requirements on the acceptable level of surface defects and imperfections that may appear on a plastic molded part. Such conditions often apply to critical components for the medical and pharmaceutical industries as well as for the manufacturers of lenses and other optical devices. However, for aesthetic reasons, many other consumer goods [...]
One of the most difficult jobs for any polisher is getting a high diamond finish on aluminum. Achieving a good shine in soft gummy material that constantly clogs stones and easily takes deep scratches from sandpaper is enough to challenge anyone. Brushing and buffing can easily lead to grooves and lines in the finished surface [...]
Annealing is the process of heating the steel to a particular temperature in the austenite region and cooling down the steel very slowly. There are many derivatives of the annealing process, but generally the process is a slow cool process. […]
Normalizing is a process that makes the grain size normal. This process is usually carried out after forging, extrusion, drawing or heavy bending operations. When steel is heated to elevated temperatures to complete the above operations, the grain of the steel will grow. In other words, the steel experiences a phenomenon called "grain growth." This leaves [...]