Midwest Mold and Texture recommends polishing the mold surface to ensure that the surface is free from flaws, smooth and uniform for optimum texturing results. However, Makino has found that, by utilizing specific milling processes, a high quality surface finish can usually be achieved without polishing.
These findings were published in a Makino Die/Mold research report, entitled "High Speed Milling on Quenched Steel " by Makoto Sato of Makino. The report stated that, "by utilizing Flush Fine and `feed equals pick' (f/P) processes advanced milling, the need for polishing is nearly eliminated."
Flush Fine is a high speed, high definition and low heat machining process pioneered by Makino. It combines high spindle speeds with precisely controlled, high pressure coolant or forced air to blast away chips and prevent heat buildup, either in the workpiece or the tool. This permits high speed machining with greater thermal stability and chip control, resulting in a superior accuracy and finish, as well as high metal removal rate and longer tool life.
Taking surface finish to an even higher level of accuracy is the f/P process, a ten year old concept verified by Makino testing. This process adjusts feed rate equally to pick rate. When compared to common machine milling, this process helps create highly accurate, smooth, more uniform surfaces.
Under common cutting conditions, uneven, rough surfaces can be traced to grooves created when the pick feed rate per revolution is smaller than the pick feed creating grooves.
The f/P method eliminates this problem. "Surface roughness is the smallest when feed equals pick for a constant machining efficiency value," the report states. "Plus, the surface area that can be machined by one tool increases when feed equals pick."
Used together, the flush fine and f/P processes allow die/molds to be efficiently machined with a superior level of accuracy and quality. This dramatically impacts several areas of the mold making process which, in turn, reduces lead time and cost.
Nearly eliminate the need for polishing - When tested, a mold maker verified that there is no visible difference between the embossed surface where polishing was omitted and the embossed surface created using the Flush Fine and f/P techniques. Manual adjusting and core polishing of embossed surfaces are eliminated, allowing mold makers to create molds in an eighth of the time.
Dramatically reduce machining time - The report documents a typical mold process duration shrinking from one week to one half day long. This is possible when flush fine and f/P cutting is used in the machining process -- in the above example, the cutting time of four tools was 3.2 times faster than conventional techniques.
Eliminate other processes - The above time savings is increased when calculating time saved through process elimination. This means that the mold maker can take a mold straight from milling to texturing.
These benefits combine to create much higher production throughput and a reduction in lead time, all while enhancing the texturing process.
Located at the edge of the Clermont County Airport in Batavia Township, a suburb of Cincinnati, Ohio, Midwest Mold and Texture consists of two independent divisions. Combined activities of the Mold Division and the Texture Division involve building, modifying, repairing and texturing molds. The parent company of the Texture Division, Tanazawa Hakkosha, was established in the early 1900s, and is a pioneer and worldwide leader in the etching industry. Tanazawa Hakkosha is a developer of unique processes for producing textures.