Part per hour

Injection molding is a high-volume production technique for turning out thousands of plastic parts per hour. An extruder melts and mixes plastic as above and then forces or injects molten material into a mold that has the shape of the final object. The plastic inside the mold cools, and the mold opens and ejects the part(s). The mold closes, and the cycle repeats. See Figure 8-2. Injection molding enables the mass production of complex shapes... 

Speed is the most important feature of induction heating. Workpiece heating rates greater than 40°C/s are possible. One supplier of induction curing epoxy adhesives claims production speeds of 600 parts per/hour are possible.21... 

A reaction vessel equipped with a Dean-Stark decanter was charged with 10 parts of the condensation polymer of 2,2-bis(hydroxymethyl)propionic acid having a Mn of 2920 daltons, a Mw of4280 daltons, and a PDI of 1.47. This mixture was then treated with tin(di(chloro-dimethylsiloxy)-tin chlorodimethylsilane) (0.25 parts), ethyl acrylate (100 parts), and hydroquinone (0.05 parts). The mixture was then heated to between 92°C and 95°C so that the amount of distillate to the decanter was 15 to 20 parts per hour. Fresh ethyl acrylate was added to the reaction vessel as needed while the reaction continued for 20 hours. 

Rotary or reciprocating hot stamp press. Dies. Highspeed equipment handles up to 6000 parts per hour. 

The overall production time is just two and a half minutes per part. Being a two-station plant, this equipment can produce close to 50 finished parts per hour - without a dedicated operator. 

Fortunately, advanced robotic equipment has been developed and is commercially available for accurate, high-speed placement of components. Entry-level automated placement machines canplace 3,000-5,000 parts per hour while mid-range equipment, that can hold more feeders, can place 8,000-10,000 parts per hour. On the high-end, placement speeds of30,000... 

Let us look at a couple of examples. If an application calls for 0.250-in.-thick by 24-in.-wide steel with a 36-in. feed length running at 30 strokes per minute, a 10,000 lb. coil with a 20-in. inner diameter (I.D.) will yield about 163 parts and the run time between coil changes will only be about 5 4 min. If it takes 10 min. to load and thread a new coil, then the net yield will be roughly 630 parts per hour if we ignore time for breaks, set up, maintenance, and repairs. If the coil weight is doubled to 20,000 lbs., a coil will yield about 327 parts. The run time between coil changes would increase to nearly 11 min and the net yield will increase by 48% to about 935 parts per hour. In this case, the additional cost... 

Resonance spectroscopy is a low power, CW application used for quality inspection. It is used to test the quality of mass-produced components because it is fast and the cost per test is low. A test sample is injected with CW ultrasound or sound at one transducer and the response at a second transducer is measured. A spectmm is built-up by stepping over many frequencies. Continuous wave excitation fills the sample under test with ultrasoimd, allowing waves from relatively distant parts of the sample to reach the receiver and contribute to the spectmm. A whole sample canbe tested without any scanning and interpretation is done automatically by computer, typically using a trained artificial neural network, resulting in short testing times. The time to complete a full test of, 100 test frequencies on an automotive component could be as short as 1 sec so that more than 1000 parts per hour can be tested. Resonance spectroscopy is suitable for 100% quality assurance of mass-produced parts. 

The cycle time has an important bearing on the investment required to automate the system and the number of operators or workstations that may be necessary. Whether manual, semi-automatic or automatic, the dispensing equipment system specified will depend on the type of application and workplace conditions, such as dispense rate, parts per hour, operator availability and materials handling. Adhesive dispense systems are available for most production lines varying from bench-top applicators to fully automated robotic units with dispense times of <50 ms. 

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. 

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