Single Cavity Tools

The initial stages of a new project will include the design and manufacture of a single cavity tool that will allow the production of sample parts. This should fulfil two objectives  

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The task of initial set-up really starts at the single cavity trial stage. If the reader has arrived at this point with a production tool and without experience of a prototype single cavity tool then a difficult time may be forecast Whether the task involves single or multi-cavity tooling, setting up should follow the same broad principles. The steps are ... 

Experiments are conducted in a single stage Aoki SB3 -100 H -15 with a single cavity tool. A 375 ml conventional carbonated soft drink (CSD) beverage container with Champagne base is used for each experiment. The PET preform temperature is recorded via... 

Relative tooling cost, single cavity Lowest. Machined aluminum may be variable, depending on quantity required 20 percent more. Hardened-steel tooling 20 percent to 25 percent more. Compression-molding steel tools... 

Compound tools are single-station tools with either single or multiple cavities. The internal and external contours of a part are blanked simultaneously during fineblanking action. Produced parts exhibit a high degree of flatness and position... 

Single impression tool, centrally filled from a sprue gate (i.e. no runner needed, the cavity filling from the sprue directly). The central boss part is of greater thickness than the rest of the moulding it is cooled with a large volume of ambient temperature water to balance its cooling rate with that of the other parts. 

Moulding tools are of the same materials and finish as described for compression-moulding tools but without, of course, the need for a powder cavity. They are generally more expensive than compression-moulding tools but, because of the higher production rates of injection moulding, it is possible to use smaller, i.e. single-cavity, and hence cheaper tools and maintain the same... 

The horizontal flash which is produced by the slight opening of the tool when the full press pressure is applied, depends on the grade of material being moulded and also on the number of cavities in the tool. For single cavity... 

One useful technique for decreasing the effective cycle time for most processes is to build molds that are capable of producing multiple parts per cycle. For example, a part running on a 60-second cycle in a single cavity mold will produce 60 parts per hour. If a 16-cavity mold is deployed, on the order of 960 parts can be produced in an hour. Multiple cavities will raise tooling costs, but may have the effect of dramatically lowering the processing costs associated with each part. 

All operations take place simultaneously in different stations. Sixteen stations were commonly used in earlier machines with outputs between 500 and 1000 TPM and tablet diameters up to 15 mm. Presses with outputs orders of magnitude greater than the above are now widely available. The dies are filled as they pass beneath a stationary feed frame, which may be fitted with paddles to aid material transfer. The die cavities are completely filled and excess ejected prior to compression. Compression involves the movement of both punches between compression rolls, in contrast to single station operations where only the upper punch effects compression. Ejection occurs as both punches are moved away from the die on cam tracks until the tablet is completely clear of the die, at which point it hits the edge of the feed frame and is knocked off the press. Tooling pressure may be exerted hydraulically, rather than through the use of mechanical camming actions, as is the case with machines produced by Courtoy. 

Tool coatings/platings are typically used to enhance tool performance in one or more of the following areas wear resistance, corrosion resistance, improved tool release, resizes components, and/or their combination. No single treatment is ideal for solving all these problems. Treatments are used that resist the corrosion damage inflicted by chemicals such as hydrochloric acid when processing PVC, formic acid or formaldehyde with acetals, and oxidation caused by interaction between tools and moisture in the plant atmosphere. Release problems require treatments that decrease friction and increase lubricity in mold cavities.3... 

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