ROSEMONT, ILL. — For caps processors, taking advantage of current trends in machinery and manufacturing can help to gain an edge on the competition.
A group of speakers discussed machinery issues during a panel discussion at Plastics Caps & Closures 2014, held in Rosemont.
The panel included Robert Beard, president of Robert A. Beard & Associates; Michael Gould, director of beverage closure solutions, Americas, for Husky Injection Molding Systems Ltd.; Mike Uhrain, technical sales manager, packaging for Sumitomo (SHI) Demag; and John Ward, vice president of sales and marketing for Arburg Inc.
Beard offered attendees at Plastics News' fourth annual event an overview of conformal cooling for injection molds.
“If you are not using conformal cooling, it is almost a sure bet your competitors are,” he said.
Beard explained that conventional molds include straight-line cooling channels, while conformal cooling utilizes cooling lines in an injection mold that curve and follow the geometry of a part to be produced.
As part of conformal cooling, copper pins can be inserted into molds to draw heat out of hot spots. In addition to reducing cycle time, these techniques also can help to reduce warpage.
Beard told attendees that conformal cooling can be utilized as a tool to help decrease rejects, which reduces the risk of a costly recall.
“Because conformal cooling yields uniform part cooling, molded-in stress can be reduced,” he noted. “As a result, you can produce a stronger part, which increases part safety. This can mitigate part-failure and recall risk.”
Moreover, molders who utilize conformal cooling can expect to realize a 10 percent reduction in mold cycle time, even with little or no engineering analysis. Increasing the engineering analysis conducted — including flow analysis, computational fluid dynamics — a higher quality mold and reduced cycle time can be achieved.
“You can realize a cycle-time reduction range for a properly engineered, conformally cooled mold of 20 percent to 40 percent,” Beard said.
With a reduced cycle time reduction of 40 percent, molders can achieve a 55 percent increase in operating income.
Beard pointed out that a cycle reduction and increase in operating income can give you options. You can either keep the additional profits or you can use a portion of the profit to lower your prices to gain more business to fill any unused press capacity.
Driving innovations
Gould, Uhrain and Ward each discussed closure manufacturing innovations.
“We want to empower the operator to get the most efficiency out of their machinery investment,” Gould noted.
From a machinery manufacturer's standpoint, Gould noted that a key to helping processors get the most from their equipment investment includes thinking beyond the hardware, including system intelligence, procedures and training to deliver lower cycle times, higher uptime and consistent part quality.
As a system supplier, Gould said a challenge for Husky is finding good people and training them to be able to solve customers' problems in the field.
“A lot of our customers have told us that one of their biggest challenges is hiring, and retaining those people,” he said. “We have tried to look at how we can make the user experience as simple as possible and most importantly, as repeatable as possible to get the most efficiency out of the manufacturing system.”
To achieve this, it is key to remove any artificial barriers that come with putting a system together and owning and operating it going forward. This can start with tooling.
Additionally, Gould noted that focusing on systems intelligence, procedures at the operator level and training, can help customers get the most out of their machinery investment.
Automated technology, such as notifications when a machine is out of specification, can help companies adjust to problems in real time, saving money.
Another trend, according to Gould, is mold identification. The mold is tagged and companies can develop a history for that mold, helping to develop maintenance procedures and manage the lifespan of the mold.
Smart start/stop can help to simplify operations, expedite recovery and minimize variability.
Automated color change features can help caps processors get consistent production.
“Sometimes the most simple things are right in front of us in terms of innovation,” Gould said. “One was the impact of the hot runner on color change time. Going from a diverted tip to an HT-6 six-bolt tip had the impact of reducing color change time by 50 percent. We want from 120 shots going from red to clear to 60 shots. In time, that was more than three minutes.”
During his presentation, Uhrain focused on a collaborative approach to achieving ultra-high-speed injection molded caps production.
“It isn't enough to just have the fastest machine or the best mold cooling or the best resin,” he said. “It is all of these things put together to achieve a culture of high-speed caps production.”
Production cell solutions for injection molding include part design, resin and production.
“Parts have to be designed to address a number of issues, from the opening and closing torques,” he said. “You also have to be adaptable to various bottle necks. Caps always are getting lighter and lighter.”
Bottle necks have moved from the old 1810 standard that weighed 2.6 grams to the current 1881 light, which tips the scales at 2.1 grams.
“You also can use a number of materials to make a beverage closure,” Uhrain noted. “Most are HDPE.”
The material has a melt flow index of 0.8 to 22, which Uhrain said has an effect on plasticizing torque and injection pressure.
It also is key to utilize the same logistics for the resin supply to avoid any contaminants.
Whether you are making one closure or 100 closures, to build the mold properly and make a proper part, the injection time must be the same. The pressure as well as injection and cooling times must also be consistent.
“Plasticizing rate will depend on the screw specification,” Uhrain noted.
In process parameters, the temperature of the melt is 450° F.
Uhrain added that there a several mold considerations to consider to ensure consistency, including dimensions, cooling system, hot runner system, slides system for a TE band, injection force, maintenance and cavitation.
“For high-speed beverage closures, people are gravitating toward 96 cavities,” he noted.
Resin and masterbatch supply also is a consideration for processors, along with metal separators, mold cooling, chiller, dry air systems as well as hotrunner control, including connections to the mold.
One example cited by Uhrain is the impact of a dry air system, which dries the molding area, eliminating condensation or corrosion. This can lead to faster cycles since you can run the mold cooler.
“Ultimately, the injection molding machines must have accuracy, consistency and reliability,” he said. “You want strong clamp design and good shot consistency.”
Arburg's Ward discussed high-output injection molding systems for 2C closures. Focusing on mold and machine technology.
Ward discussed several types of stack turning technology, including Gram, Turn-Stack, Foboha Cube , TIM and Index Cube options.
“A lot of closures that you see today are highly engineered,” he said.
The commercial benefits of cube technology include approximately 7.4 percent less production cost per part, which can result in 73 percent higher profits per year.
Foboha is a four-sided center block technology which can help reduce cycle time. It also comes in a double-cube technology that features two turning cubes into three split lines. It has co-rotating or counter-rotating indexing for flexible production.
Ward noted that the advantages of cube compared to conventional rotation technology include a higher number of cavities with the same clamping surface and clamping force, shorter cycle times and inserts that can be introduced during the molding process.
“Additional production steps are possible on the pre-molded part,” Ward said. “You also can achieve high-quality parts with central application of force. There is no tilting of the clamping unit.”
Ward also pointed out that electric cube technology can help molders achieve additional savings compared to a hybrid cube system, including cycle time reductions of up to a second and a 40 percent reduction in energy consumption.
“There is a higher investment of about 25 percent,” he added. “There is a justification in the higher cost investment based on the cost-per-part.”
