A decade ago, processors doing small-parts injection molding or extrusion of thin medical tubing or multi-layer products would have been hard pressed to find auxiliary equipment sized small enough for their needs.
Standard-size blenders, dryers, loaders, chillers, and granulators were too large for emerging applications in medical, electronic, automotive, and communications markets. Examples included cellular-phone flaps, hand-held organizers, toys, and compact discs. This disparity has become even more glaring with the recent growth in "micro-molding" of parts weighing less than a gram. Applications include watch gears, mini optical lenses, and tiny electrical parts. In one example, two wiring bobbins plus the runner weigh a total of less than 1 g. The parts are so small that dimensional checks must be performed under a microscope. These parts are being molded in only one- or two-cavity tools. "Some customers have requirements of one-tenth of a pound of material per hour, with accuracy of ±0.25% at 2 sigma [two standard deviations divided by the mean]," says Don Dunnington of K-Tron America.
Conventional auxiliary equipment moves hundreds of pounds and hour in injection applications and thousands of pounds an hour for extrusion. Such equipment sits rather uncomfortably atop molding presses of under 100 tons that process less than 120 lb/hr, or extruders with up to 2-in. screws running 700 lb/hr or less.
"We discovered that molders producing smaller parts had almost no alternative to a lot of manual operations. When drying small lots for instance, standard practice was to manually place a quantity of resin on a drying tray, bake it in an oven, then manually remove and transfer it to the machine hopper," says Chuck Morgan, Conair product manager for conveying products. Many times, handling smaller volumes of material involved a guy with a shovel, says Tom Rajkovich, president of Comet Automation. Moving small material volumes, either through manual handling or with larger auxiliary units, often resulted in an inaccurate measurement that could be costly if expensive resins or additives were being used.
Although most of the demand for small auxiliaries is to accompany small injection machines, extrusion also accounts for a share. The growth in extrusion of tiny medical catheters is one factor. Another is the need to equip small coextruders on multi-layer lines--e.g., barrier layers in packaging and cap layers on sheet and profiles. "There are more coextrusion film applications on the market, and with that comes multiple extruder setups to produce the films. Plant floor space has become scarce, which has created demand for smaller equipment to fit in," says Joe Robertson, president of Process Control Corp.
Sized for the job
Auxiliary-equipment suppliers have responded in recent years with a proliferation of pint-size units-- both physically smaller and able to provide lower throughputs with high accuracy. The new diminutive equipment is principally dryers, blenders, loaders, and receivers. Some of the newer offerings include zero-desiccant dryers, 15-g loaders, 0.1-g/cycle additive feeders, and low-rate granulators, blenders, chillers, and mold-temperature controllers.
"Auxiliary units being made today are at least one-third to 50% smaller in size and throughput than the smallest made five to seven years ago--and there may be more shrinking to be done," says Comet's Rajkovich. A majority of equipment suppliers surveyed confirm that they have downsized existing technology for modest throughput rates while keeping a full menu of features. For example, the controls on continuous gravimetric blenders from Process Control have been shrunk to one-eighth the previous size yet provide the same power and features, says Robertson.
"Five years ago, we didn't make a chiller smaller than 1.5 tons," says Jon Gunderson, marketing/sales manager for Advantage Engineering. Now the company offers models down to 0.25 ton.
"Even the granulators have to get smaller because the sprues and runners are," says Jim Hoffman, regional sales manager for Rapid Granulator. Rapid has added a second facility in Charleston, S.C., to build small units like its SR series granulator, sized down to a 6 x 6 in. cutting chamber.
The use of smaller auxiliary equipment frees up more space on the shop floor. In the case of central systems, auxiliaries at the processing machine may be stripped down to only a tiny just-in-time loader or additive feeder at the throat of the press or extruder, notes Lou Zavala, v.p. product marketing and engineering at AEC Inc.
Portability of small units is another option that can speed set-up and changeover times. "With smaller units, one can wheel away one dryer and wheel in another that has the next resin already dried and ready to go, so there's no need to wait," says Richard Hamilton, president of Hamilton Avtec.
While some hardware suppliers may have gotten started early, the trend to downsizing auxiliaries has picked up steam and has by now enlisted the majority of vendors. It is not possible here to catalog every small unit on the market, but we attempt to cite representative examples of this trend, with emphasis on developments in approximately the last two years.
Small batch-type and continuous gravimetric blenders are proliferating, with capacities down to micro scale. Maguire Products, the market leader in batch blenders, came out relatively recently with the Micro-Pulse vertical valve, which is said to meter as few as one or two pellets at a time. Here are some other recent or upcoming developments:
- In the past, 100% of our customers were single-component processors, but now half of all new orders come from customers doing multiple-component processing at the feed throat," says Mark Anderson, regional sales manager at Plast-Control. The firm's Gravimetric Dosing Controller (GDC) will soon feature a downsized main hopper to handle as little as 550 lb/hr for the maximum component (versus 1325 lb/hr previously), while the additive component will be sized to meter down to 2 lb/hr. The new small blenders will handle only three components, compared with nine for the larger sizes. Simplified controls will help bring unit costs down 40%, says Anderson.
- AEC/HydReclaim will come out next year with a micro-size line of its OS slide-gate blender. Current 2-4 component units extend down to the 100 lb/hr range.
- Colortronic's Smarthopper gravimetric extrusion yield control system comes in models for as little as 5 lb/hr.
- Comet Automation's Exact-A-Batch gravimetric blenders, available for two years, can handle four components to make up batches as small as 1 lb.
- Mould-tek's new GXB 2202 machine-mounted weigh blender handles four components at rates up to 180 lb/hr. It incorporates a high-accuracy pinch-valve dispenser and 32-bit microprocessor control.
- The Ultrablend II batch blender from Colortronic will make its first U.S. appearance by year's end. Four models offering 2.2- to 22-lb batches are redesigned for optimized mixing, easier control, and better sensing.
- The K-Qx micro-ingredient, loss-in-weight blender from K-Tron can handle rates down to 0.25 lb/hr. This machine-mounted model features four interchangeable metering screws to handle free-flowing pellets, resins, or powders.
- Novatec's NoviBlend 100 microblender mixes 2-4 materials at rates up to 100 lb/hr.
- Last year, Process Control developed its first batch blenders, the Guardian WX series, with capacities of 11 and 26.4 lb. It will build a 5.5-lb model for smaller machines as well.
Even the smallest dryers today (60 lb/hr and lower) offer dual desiccant beds, drying temperature up to 350 F, -40 F dewpoint, microprocessor controls, and no moving parts. Here's a sampling of the latest developments:
- The Mini-Dryer series from AEC/Whitlock has 10, 25, and 50 cfm air capacity and can convey 12-60 lb/hr.
- At year's end, Colortronic will introduce to the U.S. its CTT series dryers, which have hoppers as small as 0.25 liters and drying rates down to 4 lb/hr.
- Comet Automation first designed the 5-lb/hr model SD05 for General Motors to reduce the 12-hr residence times the auto maker faced with normal-sized dryers for nylon. Residence time with the smaller dryer is now said to be 4 hr. The SD05 has a 20-lb insulated drying hopper.
- Conair recently extended its line of small carousel (SC) dryers to include a unit for just 15 lb/hr. It can be mounted on the machine or a mobile drying/conveying (MDC) cart, which combines dryer, hopper, and loader. Conair says it is also working on a novel drying system for micro molding.
- Dri-Air, which was one of the first companies to develop a small dryer back in the 1970s, is designing a machine-mounted unit with a 5-lb hopper that can dispense 1-2 lb/hr of material without bridging, says sales manager Herb Wishow. Dri-Air presently offers a range of machine mounted, floor-mounted, and portable dryers with two and four beds in capacities from 15 to 200 lb/hr. A new mini-dryer processes under 10 lb/hr.
- Novatec has introduced a line of micro-dryers (MD) and a combination Dryer Conveyor System (DCS) to dry as little as 15 lb/hr of material using twin desiccant beds.
- A new three-desiccant-bed dryer with 6-lb/hr capacity will be introduced at next year's NPE in Chicago by Thoreson McCosh. A closed-loop loading system will be optional.
- Universal Dynamics is now introducing Autodry, an all-stainless, automated, and compact unit (18-24 in. diam. and 29-38 in. high) that operates automatically without blower, desiccant, valves, or moving parts. The closed-loop dry-air-flow model is said to use less power than desiccant systems.
- The Excel 30 dryer from Walton/Stout dries up to 30 lb/hr. The machine- or floor-mounted unit can control up to six plenum hoppers.
A number of recent entries use vacuum or compressed air to move handfuls of material from a central or press-side container to the machine throat:
- AEC/Whitlock offers two new sizes of its SR line of stainless-steel hopper loaders. The SR-01 loads up to 3.5 lb at a time and the SR-02 loads up to 7 lb. Suitable for 0.5-in. to 2-in. extruders, the units inherit similar technology seen on the firm's 25-lb and 50-lb capacity models.
- The HLJIT hopper loader from Comet Automation has been shrunk to a 3-lb/hr size for minor-ingredient loading.
- The new series 3000 compressed-air loader from Hamilton-Avtec can deliver 5 lb/hr to the throat of the machine as a press-side or central unit. It can dispense shot sizes as low as 15 g.
- A filterless mini receiver from Maguire has a capacity of 1.1 lb. The Clear-Vu loading system uses a slide-gate system to dispense as little as 1 g of material accurately.
- Motan says its new Metro 2 and Metro 6 portable loaders use filterless vacuum receivers in 2- and 10-lb sizes for small molding applications.
- Mould-tek's VLC-301/MV vacuum loader has a 0.3-cu-ft hopper that holds up to 10 lb. Adjust shot size down to a few ounces with the positive vacuum valve, which dispenses material from the loader into a sight glass before it enters the feed throat.
- Universal Dynamics recently acquired Autoload and its small compressed-air loader line. The company sees this acquisition as an important strategic move aimed at the small-machine market. The Autoload Jr. can load up to 100 lb/hr of material with compressed air. The unit has a 4 in. diam. and is less than 14 in. tall.
- Meanwhile, an NPE '97 entry from Una-Dyn was the KFG-50 beside-the-press loader that has a transparent hopper. Throughput is up to 110 lb/hr. Other recent entries from Una-Dyn are the LS4GT self-contained, press-side vacuum loader (100 lb/hr); and the Dimension Aspirator Valve self-contained loader, a machine-mounted unit for 50-150 lb/hr.
- The compressed-air PelletMover from Walton/Stout is an all-stainless, machine-mounted unit that can be sized to hold a maximum of 1 lb of material in one or two components. It consists of a filter, receiver cone, sight-glass, and sensor, along with pick-up hose and wand.
Feeders for small appetites
The new Graviblend S low-rate additive blender from Colortronic provides continuous loss-in-weight feeding at rates down to 0.1 g/cycle or 0.25 lb/hr using its digital disk technology. The firm also developed the Colorblend S additive feeder to dose virgin and masterbatch at throughputs less than 33 lb/hr. It works on a venturi principle.
Comet Automation's new model PF-1200 feeds non-free-flowing powders at rates down to 5 lb/hr. It is said to be accurate to ±0.5%. The compact unit extends just 20 in. from the centerline of the feed throat. And for pellets, Comet's model 1000-SM reportedly can run at 0.5 g/cycle with 0.5% accuracy. Comet eliminated the pulsing of an auger screw by substituting a helix coil, which continuously drives a column of material.
The new BAF Series volumetric disk feeder from Conair adds small quantities of minor ingredients to the primary material just before it enters the feed throat. Designed specifically for small molding machines and extruders, the BAF feeder meters down to a fraction of a gram/sec.
Motan's new three-model ECO line of additive feeders uses an inclined auger to feed 0.22 to 44 lb/hr.
Chillers & MTCs
Highly efficient scroll compressors have been adopted by a number of chiller makers as a means of squeezing the equipment into a smaller package. Recent examples include the PSA line of chillers from AEC/ Application Engineering, which have a 25% smaller footprint than previous models. Iceman portable chillers of 3-10 hp from Mokon also have scroll compressors, as does a recent 5-ton model from Kleen-Rite.
Scroll compressors are also used on some models of the space-saving Sterlco Vision line from Sterling Inc. These portable units come in 0.5 to 3 hp and occupy a maximum of 20 x 31 in. Here are some other recent developments:
- Advantage Engineering introduced a smaller Ice Cube series of water-cooled chillers from 0.25 to 1 ton. The units are geared for 30-ton or smaller injection presses. They have hermetic compressors and are 33 in. tall with a footprint of 18 x 24 in.
- AEC also has a relatively new TNY mold-temperature controller whose footprint is only 12 x 12 x 18 in. It has the same range and accuracy of control as the larger units. The TCU series of mold-temperature controllers, which feature 0.75- to 7-hp motors, has been reduced in physical size by 20%.
- The new Compact series of water temperature controllers from AEC is designed for 100-ton and smaller injection presses. The compact (13 x 28 x 33 in.) unit can regulate mold temperature in a range from 32 to 300 F.
- At NPE '97, Conair introduced downsized tempTrac Plus single-zone water controllers of 0.75 to 2 hp. They have plug-in microprocessor controls that give simultaneous readings of setpoint and process temperatures.
- This month, Mokon will introduce its smallest chillers ever, the IceMan Micro Series, designed for micro-molding applications on injection machines of 50 tons or less. The air- or water-cooled models have hermetic compressors and come in 0.25-0.33 tons.
- Sterling's Sterlco Vision water-temperature controllers include a compact model 4411 with a 13 x 25 in. footprint and 0.5 to 5 hp.
- The RD line of temperature controllers from Thermal Care comes in 5- and 10-ton portable units that control water temperature up to 250 F. The models feature diagnostic lights, flow indicator, and heating or cooling control. New software features a "seal saver" program that allows the unit to cool down to 90 F before shutting off so that the seal is not left steeping in hot water.
Nibble small scrap
Small-size scrap is more efficiently handled by smaller granulators. For example, AEC/Nelmor came out with the 3-5 hp Talon 6 x 8 in. granulator for small injection presses.
Ball & Jewell's smallest model is the new Vision BPV68 6 x 8 in. model with 2-5 hp.
The new six-model GR series press-side granulator from Comet provides sprues and runner processing at rates from 17 to 132 lb/hr. The 1-7 hp units have two stator blades and six to 24 rotor blades.
The new M80 granulator from Colortronic can fit beside the press or under the press due to its low profile. It operates at 100 rpm for less dust generation. The two-bed knife unit uses a new blade geometry that imparts no thermal stress on small sprues and runners. It grinds less than 5 lb/hr.
Cumberland Engineering's new 700 series beside-the-press models come as small as 7 x 9 in. The company also introduced a 6 x 8 in. RR (reverse rotor) model that can reverse the direction of rotation to utilize the opposite knife edges when one side becomes dull.
Smaller sprues and runners can be downsized at rates up to 100 lb/hr in the new 5-hp 10 x 8 in. press-side grinder from Foremost Machine Builders. The unit comes with a very small screen size to handle the small sprues. The top-feed unit has a footprint of 22 by 22 in. and stands more upright than traditional designs. It is a two-bladed unit with an angled-cut rotor. Foremost also redesigned its HD series grinder with an offset motor for compactness.
A small model designed for robotic feeding is the Robo 810 from Granutec. It can switch from 200 to 400 rpm and grinds 30-150 lb/hr.
Super-compactness, low horsepower, and low cost are hallmarks of the unusual R-9 "Radial" granulator introduced last year by Maguire Products. The two-knife rotor is mounted at a 45¡ angle in a vertical cabinet with a footprint of only 16 in. square. It has a 6 x 7.5 in. opening and 3-5 hp drive, but grinds more than 400 lb/hr.