The big world of small injection machines.

Here's a buyers' guide to the huge variety of features, configurations and price ranges that characterize the offerings of 50 suppliers.

Small injection molding machines (under 100 tons) account for an increasing share of the number of units sold and are proliferating in the sheer variety of models and nameplates offered. According to SPI figures, shipments of U.S.-built small machines increased 35% from 1991 to 1992 and, except for a slight drop in 1990, accounted for a fairly steady increase since 1988. Of course, imports are a big part of the total picture. According to PLASTICS TECHNOLOGY'S own Manufacturing Census, 70% of all injection molding plants in North America have machines under 100 tons. That's 31,000 small machines in use today or 35.2% of the total, a proportion that has grown gradually over two decades.

WHY SMALL MACHINES?

There are many justifications for all this interest in small machines: flexibility to handle varied molding jobs, quicker startups, easier mold handling, and often lower tooling costs. Some machine suppliers say that small machines and low cavitation are better suited to molding tight-tolerance pans because they minimize flow-balancing problems that may be encountered in large, multicavity molds.

John Johnson, Boy Machines' national sales manager, sees evidence that molders are indeed using low-tonnage machines to mold small to medium-size pans in fewer cavities. He points to a trend toward larger mold bases and smaller shot capacities.

Not all suppliers agree that small machines are inherently more accurate. Bruce Kozak, v.p. and general manager of injection molding for Cincinnati Milacron, says molders' interest in small machines shows a typical cyclical pattern. "A lot of molders are constantly improving their processes |during a product's life cycle~. They start out small and simple. Cavitation grows with their comfort level. When one product cycle runs its course, they go back to a small machine and low cavitation for the start of the next project."

This article is intended as a general overview and introductory guide to the immense variety of suppliers and small-machine choices, focusing on what is being actively marketed in North America. We classify small machines according to three basic clamp configurations: horizontal, vertical, and convertible machines, plus a fourth category of "super-mini" tabletop presses. We attempt to provide a rough idea of pricing but caution you that actual prices may vary considerably depending on which features are specified.

Small Horizontal Clamps

* Battenfeld of America: New, competitively priced Plus series is aimed at general-purpose molding. Two-tiebar, hydraulic-clamp machines of 27.5 and 38.5 tons have a "user-friendly" Unilog 1020 digital controller. Base price of the 38.5-tonner is $26,700.

Battenfeld also offers CDC (hydraulic) and CDK (toggle) series starting around 11 tons. Both utilize the same modular design and are targeted for precision molding. Base price of a 66-ton machine with closed-loop Unilog 4000 controls and 4.3-oz shot size is around $67,400.

* Boy Machines Inc.: Three series of hydraulic machines offer a range of control options. The S series (24 tons) has either manually adjustable valves or Dipronic controls with digital adjustment of pressure and speed. T2 series (40, 55, and 88 tons) has Diptonic controls, and 55- and 88-ton machines now combine the Dipronic with EPQ control that provides closed-loop pressure and speed control on the pump, plus closed-loop control of pressure on the process. The M series (40, 55, and 88 tons) has Mipronic-Plus microprocessor control, with the EPQ feature on 55- and 88-tonners.

A wide range of interchangeable injection units (e.g., six on the 24-tonner) swivel out for easy changing and realignment of nozzle, screw, or entire unit. Price of a 50-ton machine with digital and EPQ closed-loop controls is around $43,000.

* Bucher, Inc.: Company specializes in machines for thermosets, though it recently expanded into thermoplastics. All its small machines are new entries: The TS type for thermosets (25 and 45 tons), built for Bucher by Hull Corp., has hydraulic clamp, thick platens, Texas Instruments Turbo Mold control, and special sequences for injection/compression. New 88-ton SGA model, built in Switzerland by Fahr Bucher, has clamping cylinders on each of the four tiebars. It's designed for high-speed molding of thermoplastics and thermosets. Base price of a TS 45 for thermosets is approx. $80.000.

* Chen Hsong, rep. by New Pacific Machinery: Toggle machines (50 and 80 tons) from Taiwan boast wide debar spacing, low energy consumption choice of three injection units, and injection pressures to 34,000 psi. Prices run $35.000-42,000) depending on options.

* Cincinnati Milacron, U.S. Plastics Machinery Div.: Low cost, high repeatability. and reliability are key design concepts behind the Sentry line of small mono-toggle machines (33.55, and 85 tons) introduced two years ago. Normally optional features have been made standard, including closed-loop control of screw rpm, injection pressure and velocity, and mold-protection pressure. Two control levels are offered: standard VSt control or upgraded VSx control with SPC and various other options. Hydraulics include a variable-volume pump. Sentry also features 11 stages of injection pressure, five stages of screw rpm, and up to 30,000-psi injection pressure. Approx. price of the VSt 55 Sentry is around $43,000.

Milacron also offers all-electric ACT machines with 33-, 55-, and 82.5-ton toggle clamps. Using a-c servo drives for clamping, injection, screw rotation, and ejection stroke, these machines are said to be highly precise, quiet, and clean because of their oilless operation. They are also relatively expensive, but energy use is claimed to be 20-25% lower than a comparable hydraulic machine.

* CLF, rep. by Advanced Injection Machinery: Taiwanese 85-ton five-point toggle press features extra-thick, wide platens, adjustable platen support, digital setting of speeds and pressures, five stages of injection speed and pressure, core pull, and SPI knockout pattern.

* Engel Canada Ltd.: Hydraulic and toggle clamps in tiebar and tiebarless versions are offered. Tiebarless machines (30, 60, and 90 tons) reportedly have locking forces up to 15% higher than those of conventional clamps of equivalent tonnage. They also have more usable platen area, and mold changes are easier. Base price of a 60-ton unit is around $67,000.

Hydraulic machines (30 and 55 tons) have variable-volume pumps. An 85-ton toggle machine is also offered. Base price of a 55-ton hydraulic press is about $58,000.

* Gluco Inc.: Hydraulic 20- and 40-ton models are offered for thermoplastics and thermosets.

* HPM Corp,: C series (40 and 60 tons) of hydraulic machines was recently redesigned with a number of new standard features. These include an Allen-Bradley PLC with LCD display. Ample distance between tiebars permits running extra-large molds. HPM also sells 75-ton toggle and 90-ton hydraulic machines at the small end of its larger machine series.

* Hull Corp.: Hydraulic machines of 25 and 45 tons have heavy-duty construction and Smart Mold control. Base price of the 45-ton unit is around $45,000.

* Hunter Industries: Hydromechanical-clamp machines are said to have long stroke (12-36 in.) with very little oil usage. They use either self-contained or central hydraulics. A 55-ton unit is available with either horizontal or vertical injection units and adjustable mechanical cushion. Also, a "35+"-ton double-toggle press is designed for high cycle speed. A 55-tonner running off central hydraulics costs $55,000-57,750; self-contained hydraulics cost slightly more.

* Jaco Manufacturing Co.: Wide variety of machine configurations includes 50- and 75-ton horizontal hydraulic clamps with vertical or horizontal injection units. Approx. price of a horizontal 50-ton, 2.5-oz machine is $42,000.

* Jon Wai, rep. by YCI Inc.: Supermax machines from Taiwan include moderately priced hydraulic (55 and 90 tons) and toggle (95 tons) presses. A 55-ton hydraulic unit costs $49,500; open-loop, 95-ton toggle is $47,900.

* JSW Plastics Machinery: Double-toggle machines for precision molding are offered in 33, 55, and 85 tons. Injection system uses an encoder to detect precise screw position and stabilize shot volume. Other features include energy-saving hydraulics, chrome-plated tiebars, and supported moving platen with platen guides. JE series has closed-loop on injection only. JEP series has servo-valve closed-loop control and high-speed injection. J-EL series of all-electric servo toggle presses (35, 55, and 82.5 tons) will be introduced soon.

* Kawaguchi, rep. by Tomen America: Small toggle presses of 50 and 80 tons have totally closed-loop, digital control.

* Klockner Ferromatik Desma: New K series for precision molding comes in four hydraulic models from 33 to 82 tons. "A" and "S" versions both have closed-loop control of injection speed and pressure; S version also has closed-loop damp control. New two-stage "Micro" injection unit can be used in place of reciprocating screw to increase stroke and injection control. Micro injection cylinders are capable of shot volumes as small as 0.08 oz. Micro unit can also be used as a second injection unit for two-color molding.

* Krauss-Maffei Corp.: C series of hydraulic machines introduced last year comes in 44 and 55 tons. A 65-tonner is in prototype. They have a very small footprint and an unusual clamp design with highly uniform force distribution. Clamping pressure is built up by four interlinked pressure cushions on the fixed platen. Versions are available with either fully closed-loop control or closed-loop on the clamp only.

* Lucky-Goldstar International (America), Inc.: Hydraulic IDE series in 30, 55, and 85 tons are g-p machines with open-loop microprocessor controls. The two smaller models have piston pumps on the clamp for improved precision.

* Meiki America: Hydraulic machines are of 27.5, 55, and 77 tons, the first being specialized for CD molding. These high-precision machines are closed-loop on clamp and injection. Approx. price of a 50-ton machine with SPC capability is $90,000.

* MIR U.S.A.: New MPO hydraulic series has six sizes from 25 to 90 tons.

* Mitsubishi Heavy Industries, rep. by MC Machinery Systems: Hydraulic MSS series of 16.5, 33, and 55 tons combines precise servomotor screw positioning with an energy-saving hydraulic circuit to provide stop-position repeatability within 0.004 in. and half the normal energy consumption, the company says. All machines are closed-loop on injection. Approx. price of the 55-tonner is $60,000. Mitsubishi also offers a 99-ton MJ Series hydraulic machine with special prefill valve for fast clamping and ability to eject during mold opening.

* Netstal Machinery Inc.: Two 60-ton toggle machines feature sophisticated closed-loop controls and high-speed clamp. The second version is specialized for CDs. Base price of standard model is about $110,000.

* Newbury Industries, Inc.: General-purpose 3.5- and 60-ton mono-toggle machines feature a robust design in a simple package. Mono-toggle is said to provide faster cycles and longer wear with less service than other toggles.

* Niigata Engineering Co. Ltd.: Toggle machines of 55 and 85 tons have a digital valve driven by a high-speed sequencer to control all speeds and pressures. This is said to provide excellent repeatability. A 55-ton machine costs about $59,000.

* Nissei America, Inc.: High-precision hydraulic machines targeted for tight-tolerance molding range from 11 to 88 tons. Features include ceramic-coated tiebars, greaseless bushings, fully supported platens, and self-regenerating clamp hydraulics said to provide 40%-70% energy savings. Microprocessor controls with SPC are offered with LED or electroluminescent displays. A 45-ton press with LED controls costs around $63,000, a 65-tonner runs around $73,000.

Nissei plans to introduce a lower priced line next year. It's also pursuing the CD market with a new "super-fast" PX-40 (44-ton) machine that uses a mechanical "coining" (injection/compression) process.

* Sandretto Plastics Machinery: An 85-ton toggle machine is the smallest of its Series 8 toggle line. It has closed-loop injection and clamp control. Later this year, Sandretto plans to launch a new line of small machines, though no details are available.

* Shinwa Seiki, rep. by Methods Plastics Machinery: Heavy-duty Japanese hydraulic-clamp machines are offered in 55 and 88 tons. Features include wide tiebar spacing (12.4 in. sq and 14 in. sq, respectively) and long stroke (15.5 in. and 14.5 in.). Open-loop 55-ton machine costs in the $60,000 range.

* Sodick, Inc.: Hydraulic "Tuparl"-brand machines (25, 50, and 80 tons) with two-stage injection are built in Japan for high-precision molding. They have a highly rigid clamp with position encoder. Microprocessor control includes graphic displays. Injection-compression cycle and automatic mold change are available.

* Sumitomo, rep. by SHI Plastics Machinery: Two series are offered in 27.5, 55, and 82.5 tons: hydraulic SH series and double-toggle SG model with piston-type hydraulic accumulator. Both are designed for high precision and reliability. SH series has closed-loop injection and clamp control. SG series offers four levels of control, from open-loop to totally closed-loop on injection, screw speed, and backpressure. Approx. price of an open-loop 55-ton SH model is 885,000. There's also a "Minimat" series for small precision parts in 7.7 and 16.5 tons with hydraulic clamp and reciprocating screw. A 7.7-ton Minimat sells for about 845,000. Sumitomo plans to introduce its all-electric SE series (27.5 tons) by next June.

* Tat Ming, distrib. by EMI Corp.: An economical, no-frills 22-ton hydraulic machine is built in Hong Kong to specifications developed by Cincinnati Milacron. Easy-to-use, open-loop control and leak-resistant clamp cylinder are two key features. Price is $19,500.

* Technoplas U.S.A.: High-speed injection and very precise clamp are key features of a Japanese 50-ton hydraulic machine. Injection control based on cavity-pressure profile is said to provide excellent repeatability and 0.1% shot-weight control.

* TMC Machinery of America: Competitively priced, general-purpose toggle machines from Taiwan in 60 and 90 tons have wide tiebar spacing (12.6 in. and 15.75 in. sq, respectively). Standard features include closed-loop injection control, eight-step injection-speed program, and SPC. The 60-ton machine costs under $60,000.

* Toshiba Machine Co. (America): Hydraulic machines of 58 and 86 tons have such standard features as platen supports, bimetallic barrel, on-the-fly ejection, full digital setting of clamp force, and 5 x 6 core-pull package. Controls are the same as on Toshiba's larger machines and are closed-loop on the clamp. The 58.3-ton machine sells for $82,000.

* Toyo Machinery & Metal Co., rep. by Maruka U.S.A.: Double-toggle machines for high-precision applications come in 33, 55, and 90 tons. Injection unit features four steps of back-pressure, four steps of screw speed, cushion monitoring, and automatic melt purge. Clamp's "no-lube" toggle requires bi-yearly greasing. Color CRT gives graphic display of injection. Toyo also manufactures TU series all-electric servo machines from 5.5 to 88 tons, which it plans to introduce here in January. A new 11-ton all-electric model accommodates peripheral equipment right on its frame.

* Van Dorn Demag Corp.: New German-built ET series of four small hydraulic-clamp machines (27.5-88 tons) has versatile modular design. These are Americanized versions of the Mannesmann Demag ErgoTech line introduced at K'92. Injection pressures extend to 35,000 psi. Clamp features a "flow multiplier" to achieve high speed with unusual energy efficiency. ET series is available in two versions: one for general-purpose molding and the other with closed-loop controls and suited for automation. Approx. price of an open-loop 50-tonner starts around $48,900, depending on barrel size.

Van Dorn Demag also offers two domestically built small machines. The 55 HP, a redesign of the HP Jr., was introduced last year. It offers four interchangeable injection units, three different screw/barrel combinations, and Siemens Pathfinder EL control. Price is around $58,000. One small toggle press, the 85 HT, is the lower end of its line.

* Victor Taichung Machinery Works Co., Ltd., rep. by Fortune International Inc.: Toggle presses come in 50 and 80 tons.

* Welltec U.S.A.: "Cosmo" toggle presses come in two series: E series in 55 and 85 tons with wide tiebar spacing, long stroke, and three steps of injection pressure; and C series in 99 tons with sophisticated controls, SPC, and color graphics. Approx. price of 55-ton "E" model is $38,000.

Small Vertical Clamps

* Autojectors, Inc.: C-frame hydraulic presses from 6 to 90 tons offer easy mold access, deflection-resistant frames, and shuttle or turntable configurations. Wedge-type clamps are offered on some models. First standard 90-tonner has variable-volume hydraulics and Texas Instruments Turbo Mold closed-loop controls. Cost of a 40-ton machine may run $40,000-55,000.

* Boy Machines Inc.: A 24-ton vertical hydraulic machine with Dipronic digital control takes either vertical or horizontal injection units, the latter for parting-line injection.

* Butler Designs, rep. by Matchless Machinery, Ltd.: Pneumatic toggle machines include a free-standing 9-tonner with vertical clamp and horizontal plunger.

* Cincinnati Milacron, U.S. Plastics Machinery Div.: New Vector line, starting at 35 tons is produced jointly by Autojectors and Milacron. It uses Milacron's VSx controls and injection units with choice of shuttle, rotary table, or stationary platen.

* Gluco Inc.: Wide range of hydraulic and air-operated machines (3 to 75 tons) for thermoplastics, thermosets, rubber, liquid silicone, and powdered ceramic compounds is available with vertical, angled or convertible (vertical/horizontal) injection; tiebar or C-frame clamps; rotary or shuttle tables; and reciprocating screws or plungers.

* Hull Corp.: Hydraulic 25- and 45-ton machines have heavy-duty construction, software diagnostics, and Smart Mold control.

* Illinois Precision Corp.: Hydromechanical 25- and 30-ton presses have rotary tables and air-cooled "book molds" hinged on one side. Each mold can be programmed independently.

* Jaco Manufacturing Co.: Hydraulic presses with horizontal injection include 40-, 50- and 75-ton models with three or four tiebars or C-frame. Some models take rotary or shuttle tables.

* Morgan Industries: Toggle clamps of 8 and 20 tons for short-run and prototype molding are said to have compact design and allow quick, easy tool changes.

* Multiplas, rep. by New Pacific Machinery: Taiwanese presses are available with shuttle and rotary tables, vertical or horizontal injection, and a variety of fully hydraulic clamp configurations (four-tiebar, C-frame, and a two- to four-tiebar version with damp cylinder underneath the mold table. A 50-ton machine runs $23,000-42,000.

* Newbury Industries, Inc.: C-frame 30- and 80-ton toggle presses have shuttle or rotary mold table. A 75-ton, four-tiebar model comes with shuttle table.

* Noble Machines, rep. by Garter & Associates: Company offers a 3.5-ton plunger machine and a new 7-ton hydraulic, reciprocating-screw unit capable of automatic parts loading/unloading and continuous-strip molding.

* PH Trueblood: Hydraulic 75-ton C-frame machine with horizontal injection unit has 10 x 14 in. mold area, variable-volume pumps, and optional Barber-Colman Maco 4000 closed-loop control with SPC.

* Sadaplast Americas: Specializes in custom machines for high-precision molding. A 30-ton hydraulic press with vertical clamp and injection unit comes in two versions: S2 for continuous-strip molding is a single-table press with two-stage injection at max. pressure over 40,000 psi. S3 has a rotary table unit and Arburg injection unit. Approx. prices are $110,000 for S2 and mid-$80,000 range for S3. Components are manufactured in Switzerland and assembled here.

* Vimm Machine, Inc.: A 64-ton toggle press is offered with either plunger or reciprocating screw. It uses a sliding table with multiple loading bars, said to eliminate the cost of a shuttle and second lower mold base. Prices range from $30,000 to $40,000.

Horizontal/Vertical Convertible Machines

* Arburg, Inc.: Versatility within a basic machine design is the key concept behind the various Allrounder series from 27.5 to 94 tons. Seven clamp and injection-unit configurations are possible on each of the six lines offered. Models range from the low-end K-series toggles with solid-state controls to newer, high-end C-series hydraulic machines with CRT controls. "C" machines offer the so-called "Vario" feature, which allows lateral displacement of the injection unit relative to the clamp's centerline. Models can have built-in provisions for automated mold and barrel changing.

Two different sizes of injection units cover four sizes of screws and barrels. Machines are built on a modular concept, allowing easy interchange of screws and barrels. They can be changed from thermoplastic to thermoset molding in 15 min. Controls are removable for easy troubleshooting and service. In about the middle of the price range, a 55-ton 320 H hydraulic machine with large injection unit and 5-oz barrel costs about $45,000.

* Boston Matthews Inc.: "Universal" 11-ton and 24.5-ton machines have both toggle clamps and injection units that are convertible from vertical to horizontal. A new "Combination" 11-ton machine is designed for either horizontal centerline injection or vertical insert molding; the entire housing of clamp and injection units can be rotated 90 |degrees~ with no changes in electrics or hoses. These "competitively priced" machines have relay controls.

* Gluco, Inc.: Automatic and semi-automatic presses in 20, 30 and 32 tons can have vertical C-frame or horizontal tiebar clamps (fully hydraulic), shut-tie or rotary tables (if needed), and reciprocating-screw injection unit that converts from vertical to horizontal.

* Techmire Ltd.: Uniquely designed machines of 24 and 45 tons produce small complex parts in many different ways--even as a continuous strip. The concept involves moving all segments of the mold so that two to six die segments open and close around a fixed point of pang-line injection, regardless of direction of clamping (machines are easily convertible from vertical to horizontal or both simultaneously). Core pulls are built into the machine rather than the mold, reducing tooling costs. Toggle clamping is used; rotary table is optional.

Table-Top Machines

* Butler Designs, rep. by Matchless Machinery, Ltd.: Pneumatic toggle machines are designed for shot sizes down to 0.019 g or less with high accuracy. Plunger injection unit is temperature controlled right to the gate of a part or its runner. Fully automatic, horizontal, 6-ton model has a choice of injectors with capacities of 4-14 g and pressures to 18,000 psi. Polyshot Corp. outfits Butler machines with molds and hot-runner systems in order to supply turnkey systems.

* Gluco Inc.: Air-operated models from 3 to 18 tons have vertical, two- or four-tiebar presses with angled plungers.

* MCP Equipment, rep. by TomKen Tool & Engineering, Inc.: A 5-ton, horizontal "Rabit" toggle machine is offered with pneumatic or hydraulic drive and 2- or 4-g plunger. Pneumatic model costs about $12,000. A new 15-ton pneumatic machine (0.5 or 3 oz) will later be offered with electric servo drive.

* Mini-Jector Machinery Corp.: This new company revived the "Wasp" Mini-Jector line discontinued by Newbury Industries in the early '80s (PT, Sept. '93, p. 95). Air-operated, vertical-clamp, vertical-injection, 12- and 20-ton models are planned. Wedge-clamp system uses injection nozzle pressure to force the mold against stationary clamping shoes. Manual 12-tonner is expected to cost under $5000, automatic version around $15,000.

TOUCH SCREEN DISPLAY

SYSCON-PlantStar introduces an easy to use Electroluminescent Touch Screen (ELTS) version of its popular Manufacturing-Cell Interface Module (M-CIM). The ELTS version features a rugged, high resolution, solid state display showing detailed SPC/SQC graphs, profile curves of pressure, speed and position as well as detailed setup and job data at the machine. Each M-CIM can be configured to monitor 1-16 machines and multiple M-CIMs are linked together to monitor hundreds of operations in real-time.

FIFTH GENERATION CIM 

SYSCON-PlantStar announces the FOCUS-2000 Production and Process Management System.

This fifth generation CIM system utilizes an advanced MS-Windows based Graphical User Interface (GUI), designed to be operating system independent. The GUI keeps the FOCUS-2000 "easy-to-use" with symbols, icons and mouse control, eliminating the need to learn complicated sets of commands.

The FOCUS-2000 CIM system incorporates the Ingres |TM~ Relational Database Manager for full user control over system displays and report formats via Structured Query Language (SQL). The relational database allows users to redefine existing displays and reports, or to create new ones, defining their own screens, variables and data, fields.

The FOCUS-2000 runs on a variety of computer hardware platforms (IBM, DEC, Macintosh, etc.). It is comparable with UNIX, MS-DOS, Xenix, Novell NetWare 386 and many other operating systems and networks.

EXPERT SCHEDULER

SYSCON-PlantStar's Intelligent Job Scheduler (IJS) is an expert system which uses historical data recalling how individual tools and/or products have run in specific presses to automatically create an optimum job schedule for the user. Ten years of historical data from a FOCUS system may be downloaded into US creating an instant expert system.