Düsseldorf, Germany — K 2016 marks the world premiere of KraussMaffei Group's (Hall 15/B27) PX all-electric injection molding machine — billed by the company as a modular, “made-to-measure” press so customers can mix-and-match clamping and injection units to tailor the press for specific molding needs.
“This is something that KraussMaffei has put the whole concept of the PX on, being as modular, being as flexible as possible,” said Nadine Buhmann, the machinery manufacturer's vice president of sales for injection molding machines.
At K 2016, KraussMaffei is showing all five currently available PX sizes, five machines, in clamping forces of 50, 80, 120, 160 and 200 metric tons.
The company transferred its proven modular concept used in its hydraulic series of machines to the all-electric PX. KM officials said buyers of all-electrics have been faced with limited equipment options.
“Until now, customers have most often been forced to decide between the low-budget and high-end designs,” said Hans Ulrich Golz, managing director of KraussMaffei and president of the company's injection molding machinery segment. “KraussMaffei is now presenting the first all-electric machines on the market which the customer may tailor to its specific manufacturing needs in the modular principle in the hydraulic area.”
Those features include configuring the machine with larger platens, faster injection speeds, more ejector force and the ability to be operated with food-grade lubricants, Golz said.
Buhmann said the machinery company got feedback from customers that they wanted more flexibility with their all-electric molding machines.
“What we wanted to have is a machine which is very cost effective as a standard. But you can, at any time, add your options in a way that you customize your full-electric machine in a way which is currently not available in the market,” she said. “So it means that you don't have to buy something which is much too big, or which is a little bit too small, but you optimize it exactly to your needs.”
The modular press gives molders flexibility, extending over the complete service life, from purchase to production to retrofitting. Buhmann said that flexibility is a major feature of the PX. For example, she said, a molder can retrofit from hydraulic part ejection to electric (or vice versa), core pulls, injection speed and other features, to handle a new molding application.
KM is spelling out two other big ways that make the PX adaptable. First, the injection and clamping unit can be combined individually, from a wide range of sizes. Second, versions of the PX come standard with the larger platens of the next-higher clamping force, respectively.
The machine bed of the PX is split, so the clamping unit and injection unit also can be combined — say, with large clamping units and small injection units. KM offers five injection units available for each clamping unit. Each injection unit has its own performance level and can be fitted with one of three to four different screw diameters.
These intermediate models of presses with the next-higher clamping force are identified using odd numbers — from PX 51 to PX 161. The larger clearance corresponds to an increased maximum mold weight: about 750 kilograms for the PX 51 compared to 450 kg for the PX 50. The size of the platens can be increased with odd-numbered intermediate models, meaning that the entire machine bed of the next-highest side then is used — so the higher mold weight gets the necessary linear support.
Buhmann said the idea of a split machine where you can match up different injection units and clamping units — and even change them out, later on — would be difficult to add to other, existing machine series. “If you do something like this, you have to design it from day one,” she said.
And KM points out that electric servo motors run independently of each other, allowing movements to run in parallel to each other, for high speed.
Air-cooled servomotors drive the three main axes of motion — the injection unit, plasticizing unit and clamping unit. About 60 percent of the braking energy gets converted back into electricity, for temporary storage, used by the press, or fed back to the power supply.
The PX does have some servo-hydraulics in the standard version for running each axis for the injection unit and the ejector movements. The initial movement happens between two parallel injection unit barrels, so nozzle contact force can be built up very quickly, compared to movements carried out with just one electric barrel.
On the ejector side, KM picked servo-hydraulics as standard, but customers have the option to equip the PX with an electric ejector drive.
Golz said three things matter for clamping-unit design: geometry, force and speed. “In all three areas, the PX offers options for coordinating the machine to meet individual requirements,” he said.
An open design under the clamping unit allows the molder to easily install containers or conveyors under the machine.
In the history of all-electric injection molding machines, Japanese press manufacturers pioneered the technology. “The ones who are leading in the market, have to standardize to cope with this high volume of machines they have to produce, in order to be very cost-effective,” Buhmann said. That can mean standardized machines with limited choices.
KraussMaffei designed the PX to be different, Buhmann said. “Our target is really being cost-effective, but being as modular as possible, to serve the customer on their needs.”