Overhead Crane Configurations for Plastics Manufacturing
In plastics manufacturing (injection molding machines 50–200 t per unit, blow molding machines 10–50 t, extrusion lines 5–20 t, thermoforming machines 3–8 t), the core lifting task is mold change and handling. The recommended configuration is an LD single-girder crane rated 5–10 t paired with a hydraulic die cart, plus a 1 t KBK system with a mobile gantry and an electric stacker. Kelude Heavy Industry's plastics solution focuses on fast mold change efficiency.
Across the four core plastics processes — injection molding, blow molding, extrusion, and thermoforming — the shared challenge is frequent die changes (1–5 times per day) and heavy die weights (200 kg–20 t). Downtime during die changes directly impacts production capacity. This article presents crane configurations for each of the four processes to help you cut changeover time and keep production running.
Injection Molding — Handling Large Dies and Frequent Changeovers
In an injection molding workshop, the core task is die changing, with dies weighing 200 kg–20 t and changeovers occurring 1–5 times per day. Dies consist of a mold base (standard or custom, 200 kg–10 t) plus cavity inserts (50–500 kg). Every minute of changeover downtime is lost production, costing roughly $7–$30 per minute in output value.
Recommended model: An LD single-girder electric overhead crane rated 5–10 t with a span of 12–18 m, paired with a hydraulic die cart (load capacity matched to the die weight, electrically driven into the injection molding machine's daylight opening). The die cart and crane work together: the crane lifts the die from the storage rack onto the cart, and the cart feeds it into the press for clamping and tightening.
Price Reference: LD single-girder electric crane, 5t/15m span: approx. $7,400–$14,800 per unit; hydraulic die cart: approx. $4,400–$11,900 per unit. Kelude's injection molding solution integrates die carts with crane operation for mold changes in ≤15 minutes.
Blow Molding Workshop: Mold & Head Hoisting
Blow molding dies (500 kg–8 t per set) and heads (300 kg–2 t) require regular replacement. Blow molding machines typically stand 6–10 m tall (including mold platen opening), so the crane must deliver high lifting heights. Dies are mostly aluminum or steel, and handling demands scratch and impact protection.
Recommended Model: LD type single-girder bridge crane, 5t capacity, 10–15 m span, with lifting height ≥8 m. A C-hook spreader inserts under the die for lifting and transport. The die storage area is equipped with multi-tier die racks (3t load per tier), and the crane works in tandem with the racks for storage and retrieval.
Price Reference: LD single-girder crane, 5t/12m span: approx. $5,900–$11,900 per unit; C-hook spreader: approx. $450–$890 per set. Kelude's blow molding package includes die racks and die anti-collision corner guards.
Extrusion Lines: Screw, Barrel & Die Changeovers
Extruder screws (200–2,000 kg each, 2–4 m long), barrels (500–3,000 kg), and head dies (100–500 kg) need periodic replacement—typically 0.5 to 2 times per day depending on material changes. Screws have a high length-to-diameter ratio (L/D = 25–33), so anti-bending measures are essential during hoisting.
Recommended Model: LD type single-girder electric crane, 3–5t, fitted with a dedicated screw lifting spreader (multi-point spreader beam with suspension point spacing ≤1 m to prevent screw deflection). A jib crane (1t) in the barrel area assists with heating collar installation and removal. Extrusion dies are handled with a mobile gantry (500 kg).
Price Reference: LD single-girder crane, 3t/12m span: approx. $3,000–$7,400 per unit; screw lifting spreader: approx. $740–$1,480 per set. Kelude's extrusion package includes an anti-bending screw spreader and a dedicated heating collar support bracket.
Thermoforming: Rapid Mold Change Solutions
Thermoforming molds (≤2t per set) are predominantly aluminum for superior thermal conductivity. They are compact but require frequent changes—2 to 5 times per shift. Thermoforming machines are generally compact (2–4 m × 1.5–2 m footprint) and installed in workshops with 4–6 m ceiling heights.
Recommended Model: A mobile gantry (2t capacity, 2–3 m span, fitted with an electric chain hoist) covers 2–3 thermoforming machines. The mold storage area uses drawer-style mold cabinets (500 kg load per drawer); during changeovers, molds are pulled from the drawer and lifted directly to the machine.
Price Reference: Mobile gantry, 2t: approx. $1,190–$2,220 per unit; electric chain hoist: approx. $740–$1,480 per unit. Kelude's thermoforming package combines mold cabinets with a mobile gantry quick-change system for mold changes in ≤10 minutes.
Plastics Processing: Crane Configuration Guide
| Process | recommended model | tonnage | Die Change Time | reference price |
|---|---|---|---|---|
| Injection Molding | LD+hydraulic die cart | 5~10t | ≤15Minutes | 5~18Ten Thousand |
| Blow Molding | LD+C-hook spreader+die rack | 5t | ≤20Minutes | 4~8Ten Thousand |
| Extrusion Molding | LD+screw Lifting spreader+Cantilever | 3~5t | ≤25Minutes | 2~6Ten Thousand |
| Thermoforming | mobile gantry+die Cabinet | 2t | ≤10Minutes | 0.8~2.5Ten Thousand |
Key Parameters for Plastic Products
Kelude Service Advantages for the Plastics Industry
Kelude Heavy Industry has been deeply involved in the plastics manufacturing sector for years, operating a 50,000 m² production facility certified under the ISO 9001 Quality Management System. We provide rapid mold change crane solutions for injection molding, blow molding, extrusion, and thermoforming customers.
Rapid Mold Change Solutions
Built around an LD single-girder crane combined with a hydraulic die cart and mobile gantry, our system covers rapid mold change needs across injection, blow, extrusion, and thermoforming processes — boosting mold change efficiency by over 50%.
Precision Lifting Tool Protection
Standard configuration includes a screw anti-deflection lifting spreader (multi-point Spreader Beam), C-type rubber-coated lifting tools, and mold corner guards — preventing damage or deformation to molds and screws during lifting and transport.
Mold Change Efficiency Planning
We deliver integrated mold change solutions for plastics workshops — covering workstation crane type and tonnage, die cart configuration, die rack layout, and mold change SOP planning — minimizing downtime losses.
FAQ — Mold Change Cranes for Plastics
Q: Why is a hydraulic die cart recommended for injection molding machine mold changes instead of direct crane lifting?
A: Lifting a mold directly into the injection molding machine's tie-bar gap with a crane presents several issues: ① The gap is narrow (800~1500mm wide), making hook or sling entry difficult; ② Positioning accuracy is low (±10mm), requiring manual prying with pry bars; ③ Safety hazard — the mold can swing inside the gap and strike the robot arm or ejector pins. With a hydraulic die cart: the mold is loaded onto the cart at floor level, the cart travels along the rail into the gap, and a hydraulic push rod slides the mold into the locked position. Accuracy reaches ±1mm, and the change takes ≤5 minutes. Kelude Heavy Industry standardizes on hydraulic die carts with a synchronized hydraulic cylinder control system.
Q: How can blow molding molds at heights of 6~10m be changed quickly?
A: Blow molding molds are located 6~10m up on the die rack. The change procedure: ① An LD overhead crane lifts the new mold to the side access platform beside the rack (5~8m above floor level); ② A technician on the platform removes the old mold's bolts with a specialized wrench; ③ The old mold is lowered and the new mold is lifted into the rack; ④ Bolts are torqued to spec (M24×300Nm). Total time: approximately 20~30 minutes. An upgraded approach: use a powered lifting platform (electric, 2t load capacity) so the technician works at a comfortable height — improving efficiency by 50%. Kelude offers custom lifting platform solutions.
Q: How do you prevent bending during hoisting of extrusion screws with a high slenderness ratio (L/D>30)?
A: For screws 4–6 m long with L/D>30, dead weight alone causes noticeable deflection (up to 3–5 mm at maximum). Anti-bending measures: ① Multi-point spreader beam — at least 3 lifting points spaced ≤1.5 m apart, each with manual load adjustment; ② Horizontal lifting and transport — keep the screw level (tilt angle ≤3°), avoiding bending stress; ③ Storage supports — V-shaped polyurethane cradles (one every 1.5 m). Kelude's screw lifting spreader comes standard with a 3-point spreader beam and polyurethane V-cradles.
Q: What is the recommended die storage solution for thermoforming molds that are changed frequently?
A: For thermoforming molds (aluminum, ≤2 t per set) changed frequently (2–5 times per shift), we recommend: ① Drawer-style mold racks — each drawer has a 500 kg load capacity, and molds are pulled out horizontally and lifted to the thermoforming machine; ② Product classification — frequently used molds are stored in the upper drawers (shorter pull-out distance), while less-used molds go in the lower drawers; ③ QR code on each mold set — scanning displays the storage location and the mold-change SOP. Kelude pairs these racks with a WMS mold management system.
