Flashless molding is one of several ways to reduce material waste in a rubber molding operation, and with some relatively new technologies available, it can positively affect labor costs, cure times and component quality.
John Roembke, CEO of Roembke Manufacturing and Design Inc. in Ossian, Ind., talked about flashless molding and particularly about the benefits of valve gate flashless molding during a presentation at the International Rubber Molding Conference, held April 5-6 in Dearborn, Mich.
The development of flashless molding as a waste deterrent dates back more than 50 years, followed in the past 20-25 years by updates such as cold runner, liquid injection and valve gate molding technology, Roembke said. The most recent technology is a ``zero waste'' valve gate flashless system for high-consistency materials, he said.
Companies are looking for ways to reduce costs at all levels in turbulent business climates which require innovative processes, offer limited business opportunities for unprepared firms and not enough business of multiple vendors, and challenge partner relationships, Roembke said.
There are many conventional molding costs that rubber companies have grown to accept, instead of keeping an eye on them like they should, he said. These include material-related costs like handling extra material and waste disposal; labor and supply costs for press operators, and people and supplies for washing, deflashing and inspection operations; and efficiency-related costs for running molds with blocked cavities, employee downtime and various causes of longer cure times.
If those individual costs were more closely monitored, better choices would be made regarding the type of tooling and presses needed to make profitable product, Roembke said.
The advantages of valve gating include no material waste, ease in automating the process, less labor due to automation, a realistic challenge to chemists to reduce cure times and possibly to triple the amount of heats per shift, he said.
The disadvantages of the valve gate system include requiring more disciplined processes than normal compression molding and consistent material specifications; appropriate press control, which is no good for a 30-year-old press, and a greater mold investment, Roembke said. The key factors, though, are that it requires employees willing to learn and implement the new technology, and it takes an investment in time, money and talent to successfully implement the system, he said.
In comparing the costs of a valve gate system with transfer hot pot and cold pot molding configurations, Roembke found the initial tooling costs for valve gating were indeed much higher. But the annual heats per shift were much higher in the valve gate system, and the annual waste cost was nothing while the transfer systems' were in the thousands of dollars.
The positive return from the valve gate automated process includes better quality with smaller molds and fewer rejects, and better use of an employee within a production cell, allowing the operator to run multiple presses, perform quality spot checks, clean molds and package product, Roembke said. The press operator/technician would have total accountability for the process, the product, tooling and equipment.
In using the valve gate technology, Roembke took on a project from molding company Polyneer Inc., located in New Bedford, Mass. The firm needed 60 million parts per year under the following conditions: run the project with a maximum of three presses and meet requirements of 100-percent inspection, flash-free, no imperfections and minimum material waste, he said.
The job also was to be completed-production, inspection and shipping-by only one person, he said.
The outcome yielded only one major problem, that the one technician was not fully utilized, Roembke said. The automation reduced the need for labor and eliminated waste to the point where that employee could be given more to do. The proposed solution to this ``problem'' was to add a fourth press and possibly a fifth down the road to the production cell, he said.
Roembke said he believes automation and technology can help companies improve their efficiency in this manner, but it takes investment on their part to make it happen.