When adding automation, you can''t plan too much
The game plan really depends on what processors want to accomplish and how much they have to spend. Industry experts offer advice on where to begin and how to get the most out of your investment.
Automation''s rapid ubiquity is a function of results: increased competitiveness, reduction in labor costs, improved part quality, and consistency. But how do processors figure out how to enhance operations with automation? What criteria determine the equipment that meets their needs? And how much automation can molders buy?
1. Identify your goals
"The molder must identify up front what they want to do with the automation," says Tom Schaffner, regional manager at Wittmann Inc., based in Torrington, CT. "As you would not place a person on a production line without any instruction, neither would you buy automation equipment without a purpose."
The typical purposes shouldn''t be surprising." Some of the important reasons we purchase robotics and automation equipment is to reduce the need for human resources, ensure a consistent molding process, and eliminate damage to parts falling directly on a conveyor as dictated by our applications," says Thomas Nagler, VP of custom injection molder Natech Plastics (Ronkonkoma, NY).
Either suppliers or third-party integrators can then help translate these clear and simple goals into specific solutions. You just have to decide what you''re trying to achieve, and to what degree.
"The reality is most new customers are first-time users of robots from fairly small companies," observes Joseph Portelli, plastics program manager, Fanuc Robotics North America Inc. (Rochester Hills, MI). "They often rely on the expertise of the robot supplier or want an unbiased opinion from a third-party systems integrator." Upon analyzing a molder''s operations and goals, suppliers and consultants can review parts and applications, establish payback needs, and identify options and potential labor savings. Whether a robot meets required production volume and margin on the molded product is obviously significant. And molders must identify which tasks will be automated in a given period of time so they can calculate return on investment. Payback generally takes one to two years, according to automation experts.
Processors with prior automation experience may not require guidance in demonstrating the justifications for investing. They may, however, need help identifying areas that will produce the best results.
2. Think of the big picture
Robots in the plastics industry are often used for simple pick-and-place operations. However, experts advise molders to envision the big picture, taking into account the total process from pellet to shipment.
"Some equipment can offer certain flexibility as a result of its design," Wittmann''s Schaffner points out. "For example, a sprue picker can be used to remove sprues and small parts from a mold. If you want to perform more complex operations such as packaging, cooling, or assembly of parts, then you would require a servo robot."
Robotics used in the plastics industry generally fall into one of two broad categories: gantry, beam, or traverse robots, and articulated machines. "The beam or traverse robots tend to be limited in their capability," Fanuc''s Portelli says. "Beyond extraction, you might be able to have some stacking capability, but this is fairly limited."
By comparison, articulated robots are more sophisticated and flexible. "You can do so much more," Portelli says. "You can do extraction, assembly, packaging, palletizing, sorting, deflashing, and various types of welding." These units can be reprogrammed to perform other functions as the need arises.
Because processing needs constantly change, experts advise that it''s more cost effective to consider purchasing equipment that can be used with other molds or machines. "It is always best to look at any future applications when designing a system for a specific application as it can affect many, if not all the requirements," Schaffner says.
3. Get specific
Robots cost anywhere from a few thousand to several hundred thousand dollars, which includes the equipment, training, and installation.
"For example, something as simple integrating a Pin Marker with the robot may be only a few thousand dollars, plus the cost of the equipment, and have a payback of only a few months," Wittmann''s Schaffner says. "Alternatively, a complicated automation work cell that removes multiple parts from several machines, erects and conveys boxes, and then places the various parts in the box before indexing them along a conveyor, may cost $250,000 and yet still offer an attractive payback of less than nine months." Suppliers say they can work with molders to implement automation in phases.
Natech Plastics is shopping for replacement robotics for 110-ton and 210-ton injection molding machines. The processor operates nine injection molding machines, eight of which are automated. Among the variables it is considering are equipment and delivery costs, startup and training expenses, finance terms, and historical experience with a robot brand/controller, says Nagler.
"These robots were purchased in 1998 and are wearing down, requiring significant maintenance and showing evidence of reduced speed and precision. This time we will more seriously consider all-servo technology for at least one of the two in order to keep ahead of the curve in our industry."
Last September Natech added a 110-ton all-electric Toshiba injection molding machine to address a shortage of capacity in that tonnage range.
"We had an existing 190-ton Toshiba hydraulic that did not have robotics, and as such this machine was relegated to legacy tooling that did not support robotic part removal, or other applications where the part dropping directly onto a conveyor did not affect part quality," Nagler says. "When we made the decision to purchase the machine, we decided to purchase robots for both machines, increasing the versatility of the 190-ton unit."
Natech, which runs many three-plate molds and requires robots that have both a main arm (for part removal) and sub-arm (for runner removal), relied on its suppliers to recommend the proper-sized robot for the specified machine.
"Three levels of robots are typically available today in order of increasing functionality and price," Nagler says. These include pneumatic control in all motion directions; pneumatic control in vertical and crosswise motions, with servo-motor control in the traverse direction; and servo-motor control in all motion directions.
"We decided upon type two as we could not justify the large price differential, which was two to two-and-a-half times more for the all-servo technology." GV
A material matter
As processors cut checks on a monthly basis for resin, plant utilities, labor, and rent, they likely aren''t thinking about their material handling system. But industry suppliers Nucon Wittmann, Conair, and Motan would encourage them to, saying an efficient, centralized system has a direct correlation to each of those bills.
"Our customers are fighting to be competitive," Chuck Thiele, a senior consultant with Conair (Pittsburgh, PA) says, "and in every hour of lost machine time there is money out the door."
A well-conceived, properly-designed, and effectively-implemented material handling system can offer a processor material savings, more efficient energy consumption, reduced labor, reduced floor-space needs, and greater out put. But that doesn''t mean it ranks high on many processors'' priority lists.
"My impression is that a lot of processors still see material handling as an afterthought," says Rob Miller, president of Nucon Wittmann (Markham, ON). "They don''t see how it can make them a better company; they don''t see how it can make their process more efficient. It''s just something to get resin into the feed throat."
"Processors buy their machine and maybe a robot and granulator," says Dan Saigh, national sales director for Motan (Plainwell, MI), "and then their budget is used up, and they say, ''You know what? I forgot to buy the material handling system. I have to somehow dry material and get it to these items.''"
The first and most obvious step when implementing a material handling system is an assessment of current capabilities and longer term desires. "The first thing we ask," says Miller, "is, ''What do they want to accomplish?'' Do they just want to move material?" Expanding beyond a simple point A to point B loading system, Miller says Wittmann tries to stress that the system is capable of more, and if designed properly, it can help a processor with less obvious issues like inventory control, throughput, and quality.
In order to achieve that big-picture take, Saigh breaks down a number of basic production characteristics for the plant. These include machine rates, lb/hr of material usage by machine, and drying temperatures of materials and their residence times. On the material side, Saigh determines if the resins come in bulk, gaylords, or bags, and if additives are used for coloring or process enhancement. From here, Motan creates a matrix, matching output requirements with equipment needs.
At this stage, one decision (central vs. press-side systems) will dramatically change a processor''s plant layout. "Generally, I''d say there are more beside-theâ€“press customers out there than there are central-type customers," explains Saigh. "[Moving to a centralized system] is quite a mind-shift. It''s a pretty aggressive change from the norm."
This step can also be taken incrementally to avoid the full capital impact that could come from switching over to centralized material conveying and drying in one fell swoop.
Saigh points to a recent customer, Sioux Chief (Kansas City, KS), as an example of an incremental implementation. The injection molder of plumbing fixtures installed a central conveying system only, allowing their drying hoppers to be moved off the shop floor into one location. This eliminated the need for loaders at each machine, and it also cut in half the number of dryers running.
"Their immediate savings was floor space, labor, and material," Saigh explains. "They haven''t realized energy savings yet, but that''s the next step." In the project''s second phase, Motan will replace all the individual dryers with a single, larger unit.
By pre-wiring units, laying out tubing beforehand, and implementing in shifts, installation can have a relatively negligible effect on uptime. Using a benchmark plant of 15 injection machines, Saigh says a centralized system could be installed in approximately two to three weeks, with actual machine downtime being as little as 15 minutes.
For those reluctant to make such a sweeping investment, Conair''s Thiele does the math. "If a guy''s making 20 material changes a week," Thiele says, "and every time he changes material, he has to empty the hopper, clean it, refill it, and then redry the material, he can have four hours of downtime on the material changes at least." Extrapolating further, that''s 80 hours of lost production a week—on a machine worth $75/hr, $6000/week in machine time alone.
"I was talking to a customer," Thiele says, "and he''s realizing 40 hrs/week of increased machine utilization. And this is a small guy—I think he has nine or 10 machines. He hasn''t even looked at energy or labor savings." TD
Opinions divided on roll handling automation
Despite productivity gains, high initial costs could be holding back more widespread implementation.
Blown- and cast-film suppliers have been dickering for a number of years about fully automated roll-handling systems (March 1998 MP/MPI), but they''re still not widespread, says Robert Wirtz, general manager for extrusion at equipment supplier Windmoller & Holscher (Lengerich, Germany). He says most processors don''t see a true relationship between the high costs of the systems and the benefits in output improvements they bring.
"Most of the lines we sell today include semi-automatic roll handling, which appears to be sufficient for most processors," Wirtz says. According to him, pallets or wagons used in unloading finished rolls represent the extent of automation at most processors. He believes it all comes down to costs.
(A fully automatic system generally includes shaft coring, reel unloading, conveying mechanism to a palletizing station, loading, reel inspection, placement of cardboard "headers" as edge protection, and robotic overwrap packing, says Werner Bamberger, head of automation and electronics at tenter-frame and extrusion line manufacturer Bruckner Maschinenbau, based in Siegsdorf, Germany.)
Edgar Gandelheidt, managing director and CEO of processing equipment builder Kiefel Extrusion (Worms, Germany), agrees with Wirtz about costs, and adds, "We''re also seeing more concern among our customers to improve the quality of their product. When operators unload slit film rolls by hand there is the danger of bumping the completed roll on the pallet or truck, damaging the top 2 cm of the film," he says. This results in the processor delivering less than the customer ordered—and in most cases the entire shipment is returned to the processor as unacceptable in quality.
To help processors eliminate this problem, Gandelheidt says his company is introducing a roll-handing unit with an electric shaft puller device that is attachable to a forklift (see accompanying photo). Premiering this October at the K show, the unit grabs the shaft and holds it while sliding the cored rolls gently onto trucks to prevent damage. Gandelheidt believes this low-cost innovation provides most film processors a means to improve quality while saving on investments in fully automatic systems.
Dave Finnemore, product group manager at SMS Folientechnik (Vienna, Austria) doesn''t completely agree that fully automatic roll-handling systems have not made inroads. He says within the last five years very large commodity film processors of products such as stretch wrap, including Trioplast Industries (Smalandsstenar, Sweden); Orbita-Film (WeiBandt-Golzau, Germany); BPI (Greenock, Scotland); and Manuli Deutschland (Schkopau, Germany) have all invested heavily in fully automated roll-handling systems, primarily for labor savings. Some processors rely on automatic guided vehicles (AGV) to transport finished rolls to the warehouse, but Finnemore says many see this as overkill. "Often processors say a fork lift can do the job cheaper and faster," he says.
One new element that is starting to be incorporated to fully automatic systems is an automatic roll-weighing station positioned just before the robot that picks up a reel. Finnemore says this helps eliminate returns of delivered goods that don''t meet agreed-upon roll weight and length.
"Both semi-automatic and fully automatic roll handling are growing, but not for the same-size processor group," Finnemore says. Completely automated systems (for example for 800-mm-diameter rolls of cast stretch wrap) start at €180,000/line and can go as high as €300,000/line, he says. Large processors see the value in reduced costs and better end-product quality.
"Take a country like Sweden, where an operator can earn up to €50,000/yr. In about two to three years a processor can expect a payback and be able to delegate the operator to more responsible work than off-loading," he says. "The big players, those producing 4m-wide mother rolls, processing 12,000 to 14,000 tonnes/yr of polymer, are the ones moving toward fully automatic roll handling."
Orbita-Film Managing Director Han Joachim Baumann says installation of fully automated roll handing has paid off for his company. "You shouldn''t underestimate the savings achievable by eliminating the human element," he says. End-product quality has improved substantially and payback was possible quickly, he says.
Bamberger says for lines running up to 600 m/min, manual—and even in some cases semi-automatic roll handling—are beyond the limits of how much operators can physically handle. Fully automated off-loading is mandatory in these cases, he says.
Besides speed of film output, Bamberger says that in industrialized countries regulation is the real driver of fully automated roll handling. Rules have been so refined to protect workers that in many cases fully automated roll handling is the only possible solution.
"In a transverse direction orienter or Pull Roll-/Winder-system regulations already demand that these areas be off-limits to workers and only accessible following machine shutdown in case of a mechanical problem or film break," Bamberger says.
A more prosaic consideration that may be hindering wider installation of both semi- and fully automated systems is shop floor layout, says Gandelheidt. Finnemore agrees, saying that fully automatic systems can require up to 50 sq m more space per line, which many plants just don''t have available. BC
Inmold temperature control: simple solutions yield major savings
Water temperature control, despite its fundamental importance to a processing operation, still appears to be one of the items where too many buyers think they can take shortcuts.
With processors hesitating longer than ever regarding capital expenditure decisions, currently it''s the simplest and cheapest temperature controllers drawing the highest demand. Even companies like GWK (Kierspe, Germany), best known for their plant-wide integrated systems, have been obliged to introduce budget systems.
But regardless of the fact that it''s a buyer''s market right now, the fundamental point for processors is that even the most basic system, as long as it''s set up properly, can quickly yield significant savings. Sometimes the investment required is truly minimal, since the processor has most or even all of the equipment needed, but just isn''t using it properly. Simpler still is cleaning pipework that''s gotten clogged over time, thereby limiting water pressure.
Strange but true: not everybody seems to appreciate that cooling time is money. Here are some actual case studies from GWK.
The end user of a technical molding bought in quantities of 2.5 million parts/yr requests a 5% reduction in price. An analysis of current costs at the molder indicates no room for further discounts. But the business is too important to risk losing. Is there a way out?
A look at the machine cycle shows a cooling time of 23 seconds. A thermal calculation and an evaluation of cooling channel design and temperature controller specification indicates that the actual cooling time required is 12 seconds.
A modification of the tool to incorporate conformal mold cooling (in which the cooling channels conform to the contours of the core and cavity) would cost €25,000. But the potential part cost saving is 18%, equivalent to €70,000/yr. The company went ahead with the modification, gave its customer the discount, and still managed to make a profit.
Production of a large molding needs to be increased from 400,000 to 520,000 parts/yr. But the existing machine and mold are already fully utilized at the current rate, and other machines on hand are deemed not suitable.
The investment for a second production cell (a 27,000-kN machine, peripheral equipment, and mold) would be approximately €1.8 million. But this cost cannot be covered by the income from the additional 120,000 parts/yr. Do you reject the order, and perhaps lose the entire business?
A thermal calculation and evaluation of cooling-channel design and temperature controller specification shows that a 35% cycle time reduction is possible solely through elimination of hot spots. The cost of optimizing the temperature control system is roughly €80,000—negligible in comparison to €1.8 million.
A processor running 20 machines molding technical products observes problems with his water quality. Lime scale in the pipework is affecting heat transfer in the mold, resulting in longer cycle times and product quality problems.
A thermal calculation shows that the deposits have caused a 60% increase in cooling time, and the scrap rate has quadrupled since production startup. This loss in efficiency is costing the molder nearly €2.5 million/yr.
On the other hand, installation, maintenance, and operation of centralized water treatment equipment costs approximately €50,000/yr. PM
Peter Mapleston, Bob Colvin, Tony Deligio, and Greg Valero reporting.
|Bruckner Maschinenbau GmbH||www.brueckner.de|
|Fanuc Robotics America||www.fanucrobotics.com|
|Kiefel Extrusion GmbH||www.kiefel-extrusion.com|
|SMS Folientechnik GmbH & Co. KG||www.sms-folien.com|
|Windmoller & Holscher||www.wuh-lengerich.de|
When Jeff Roque interviewed with Nucon Wittmann last September for a cost estimator position, it was a question he asked company President Rob Miller that helped land him the job and ultimately changed how the company prepares quotes and fulfills material handling system designs.
"I asked, ''Did you ever think of putting [plant schematics] in real-world or 3-D AutoCAD drawings so you could actually do a complete plant drawing with piping, coupling, and automatic takeoff?'' That''s kind of what got the ball rolling."
Several months and about 90 jobs later, Roque and Wittmann have used the program to give customers a unique perspective on their material handling system plans. Rather than using 2-D isometric drawings or blueprints, Roque takes an AutoCAD drawing of the plant with actual coordinates, imports it into AutoCAD, and drops in machines, material lines, couplings, hoppers, loaders...the works.
By rendering and manipulating the model, he can give processors multiple views of their project, letting them know when a plant floor might be getting cluttered, or a low over-hanging crane or duct might block a future material line before installation begins.
If clients have an AutoCAD drawing of their plant, Roque is off to a running start, but in about 50% of the jobs, he builds a plan from scratch. This can be done relatively quickly thanks to his 15 years of experience with the program and architectural background. Using a current job that has seven machines with blenders as an example, Roque says it will take about four hours for him to complete a schematic, and five minutes to calculate takeoff, or pipe lengths. This compares to two to three days if he drew the system by hand, and it wouldn''t offer customers the 3-D perspective of their plant.
"The average person can''t interpret a blueprint," Roque says, "but if you put it in 3-D, it becomes 100% clear what''s going on." Roque continues to add capabilities, and in the near future, he hopes to create AVI files of the layouts that could be viewed as a virtual tour on a majority of computers, versus AutoCAD files, which need an AutoCAD seat to be viewed. TD