Patented SCS process uses multiple cavities
MHI Injection Molding Machinery Inc., which sells Mitsubishi presses, is touting a newly patented process that molds with multiple cavities, filling one part at a time. The process is called SCS, which stands for ``sequential cavity separation.''
SCS allows parts with vastly different dimensions to be made using the same mold. The technology opens and closes hot-runner valve gates to fill first one part and then another - controlling the fill velocity, pressure, position and hold time of each cavity independently.
Originally, MHI used mold cavity pressure to control the process, but after beta testing, the firm discovered that not all customers had that capability. The company went back to the drawing board and developed a machine control version of SCS to allow for standard injection molding.
MHI of Bensenville, Ill., listed several advantages of sequential cavity separation:
* The clamp tonnage required to fill one cavity at a time is much less than when multiple cavities are filled at the same time. That means a smaller machine can be used. One example: automotive wheel covers with a surface area of 188 square inches per part. Normally, that part would require a press with 1,200 tons of clamping force, but MHI has molded the parts successfully on a 610-ton machine. The press size must be large enough to mold the largest part in a family mold.
* The same principle means a family of parts can be molded on one press and one work cell, such as all four major components of a laptop computer. That ability dramatically cuts costs compared with using four presses and the required auxiliary equipment.
* Material costs can be reduced by eliminating over-packing conditions often seen in multi-cavity molding, according to MHI.
* SCS also can reduce or eliminate problems with color matching, since all parts are molded on the same machine.
* The technology can be used for low-pressure molding of textiles onto automotive parts. On a door panel, for example, the machine first molds a cloth insert for the upper section, then pull back the slides that provide a seal-off between the main panel and the cloth area of the door panel. Then the substrate is injected around the cloth insert.
MHI said customers are running 12 Mitsubishi presses with the SCS option, with 11 more presses on order for delivery later this year.
Applications include automotive parts, office equipment and toilet seats and lids, although an MHI spokesman said the company would not identify customers.
Tel. (630) 693-4880, fax (630) 693-0915, e-mail [email protected]
Epco expands audits to add blow molding
Epco Machinery LLC of Fremont, Ohio, now audits extrusion blow molding machines to the ANSI/SPI safety standard B151.15-2003.
The standard was approved in late 2003, and companies must be in compliance by Oct. 15, 2006, Epco said.
Epco provides a detailed results sheet on each machine, and an estimate of how much it would cost to bring the blow molding machine up to date.
For several years, Epco has offered an NSI safety standard audit for injection molding machines.
Tel. (419) 334-2631, fax (419) 334-2840, e-mail [email protected]
Deformable die rings available from BMC
BMC Controls Ltd. of Gloucestershire, England, now is making 3DX deformable die rings for extrusion blow molding.
Deformable die rings are used to optimize material distribution on industry containers, drums and automotive moldings.
For the 3DX, the conventional die is replaced with a special ``flexible'' die ring that is pushed and pulled into an oval shape by hydraulic cylinders as the parison extrudes.
According to BMC, its die rings are synchronized to the normal axial thickness control to ensure repeatability of parison thickness.
The process is controlled by a programmable profile similar to a parison programmer.
BMC said that, unlike competing products, 3DX has been designed so end users can maintain the system themselves.
When conventional die rings are retrofitted to machines with a fast material flow, the flexing of the die may have to be limited to prevent the parison from ``folding,'' BMC said.
But BMC claims it has overcome that problem by fitting a proportional valve to control the initial speed.
Tel. +44 (1242) 604-040, fax +44 (1242) 603-987, e-mail [email protected]
Bishop Vibes2 screw reduces barrel leaks
If melted plastic leaks from the bottom of your vertical injection blow molding machine, take heart. Bishop Tool & Design Inc. has an answer: a screw called Vibes2.
Bishop Tool of Mount Holly, N.J., designs and makes single-stage screws for extrusion, blow molding and injection molding. Vibes2 has undergone a six-year field test.
The design includes corrected opposing pressures with a special deflection angle, which creates an impassable area that contains the material.
In all test cases, the configuration has eliminated leakage of the homogenized compound, Bishop Tool said.
The company even installed the screw in worn barrels where processors were losing as much as 25 percent of the material. The Vibes2 screw has cut that amount to less than 1 percent.
Bishop Tool can build new Vibes2 screws or modify the shank of an existing screw when it is being rebuilt.
Tel. (888) 428-6657, fax (609) 261-7226, e-mail [email protected]