Table of Contents
1. What a 20L Paint Bucket Extrusion Blow Molding Machine Is
A 20L paint bucket extrusion blow molding machine is a production system that forms large open-top containers directly from plastic resin. The machine melts a polyolefin compound, extrudes a hollow tube called a parison, captures that parison inside a split mold, inflates it with compressed air until the melt presses against the cold cavity wall, and then cools the part into a rigid 20 liter pail. Because the container is created in one continuous operation from raw pellet to finished bucket, the process is fast, material efficient, and well suited to high volume packaging for paints, coatings, adhesives, and construction chemicals.
The defining feature of this class of equipment is the wide mouth. A standard 20 liter paint pail has an opening nearly as large as the body, which lets users pour thick coatings, scoop product with a tool, and fit a brush or roller directly into the container. That geometry is harder to mold than a narrow neck bottle because the parison must open into a broad shape and the part must keep straight walls, a flat top ledge, and a sealed rim. The machine therefore combines a large accumulator die head, a wide-section mold, and precise clamp control so the open mouth stays round and the wall stays uniform.
Leak-proof design is the second defining requirement. Paint and coating products are viscous but they migrate through the smallest defect, and a pail that weeps at the seam or the handle boss creates returns, stains, and lost trust. A purpose built machine manages wall thickness at the bottom weld, the side seam, and the handle area so every joint is solid. Combined with a well formed lid seat, the result is a pail that holds liquid product for months without seepage.
Wanplas, as the main brand of a group with an average of more than ten years of experience on each equipment type, supplies the extrusion blow molding machines and upstream compound lines that turn raw resin into consistent, printable, leak-free pails. A producer can begin with a single station machine and later add a second station or a multi cavity mold using the same engineering platform.
How extrusion blow molding differs from other methods
Injection molding fills a closed steel cavity with molten plastic under high pressure and produces a finished shape with no hollow interior unless a core is used. Extrusion blow molding instead builds a hollow shell by inflating a parison, which is the natural way to make a seamless open pail. Rotational molding works for very large or complex hollow parts but runs slowly and cannot hold the tight wall tolerance a paint pail needs. For a 20 liter open container at industrial volume, extrusion blow molding is the most balanced choice on cost, speed, and part quality.
Single station versus double station layout
A single station machine has one clamp that opens and closes on one mold. A double station machine carries two clamps on a rotating or shuttle platen so one cavity cools while the other is being filled, lifting output substantially. For a 20 liter paint pail at moderate volume, a single station with a one or two cavity mold is often enough. At higher demand, a double station with two cavities per side doubles the hourly count. The layout choice sets the footprint, the power draw, and the labor needed per shift.
2. Why a Dedicated Machine for Paint and Coating Pails
A general purpose blow molder can make many shapes, but paint and coating pails carry special rules. The product is heavy, the mouth is wide, the wall must survive dropping and stacking, and the seal must hold thin liquids. A dedicated 20L paint bucket machine bakes these rules into the head, mold, and control logic so the operator spends time running rather than fighting the equipment.
Wide mouth parts need a die head that opens the parison into a broad tube without pinching the melt. A head built for narrow bottles would distort the parison and create thin spots near the rim. The dedicated head spreads the melt evenly around a large mandrel and keeps the wall balanced from the bottom to the lip, which is exactly where a paint pail fails first.
Consistency across batches
A coating plant ships thousands of identical pails, and a distributor expects every lid to fit every pail. A dedicated machine repeats the same parison weight, the same blow pressure curve, and the same cooling time on every cycle. That repeatability protects the lid seat tolerance so a lid snaps on the same way on pail number one and pail number ten thousand. Losing that consistency means lids that leak or rattle, which a paint brand cannot accept.
Handling heavy filled weight
A full 20 liter pail of coating weighs roughly 25 to 30 kilograms. The empty pail must therefore have wall strength at the handle boss and the base without becoming so thick that material cost rises. A dedicated machine tunes wall distribution so the handle and bottom carry extra resin while the side wall stays lean. This balance is hard to reach on a machine tuned for light consumer bottles.
3. Wide Mouth and Leak-Proof Bucket Design Requirements
The bucket geometry drives the machine design. A 20 liter paint pail typically measures about 290 to 310 millimeters across the top, 270 to 290 millimeters at the base, and 350 to 400 millimeters tall. The mouth opening is close to the top diameter, leaving only a short rim ledge that holds the lid. That short ledge is the most important sealing surface on the part.
Wide mouth geometry and the rim ledge
The rim ledge must be flat, round, and free of flash so the lid gasket seats evenly. A dedicated blow molder shapes the top of the parison with a calibrated neck ring that forms the ledge in the mold rather than by a later cut. This integrated forming avoids a trimmed edge that could leak. The wide mouth also needs a slight taper so the pail releases from the cavity without dragging the rim out of round.
Leak-proof bottom and side seam
The bottom of a paint pail is a pinch welded seam where the two parison halves meet. If that weld is thin or contaminated, coating seeps through. The machine controls pinch pressure, pinch temperature, and parison overlap so the bottom weld reaches full wall thickness. The side seam from the parting line is handled the same way, with enough melt and clamp force to fuse the surfaces. A leak-proof pail is mostly a story of a clean, hot, well pressed weld.
Handle and reinforcement ribs
Many 20 liter pails carry a side or top handle so a user can carry the filled container. The handle boss is a thick section that must bond to the thin wall without a void. The mold includes a local cavity that packs extra resin into the boss while the control system holds enough pressure to fill it. Reinforcement ribs around the body keep the pail round under stacked load and resist bulge when the product expands in heat. The machine must hold the wall thin enough to be economical yet structured enough to carry these features.
Stacking and lid fit
Pails stack several high in a warehouse, so the top rim must seat into the base of the pail above without slipping. The mold forms a stacking ring that nests securely. The lid itself is usually made on a separate injection machine, but the pail mouth tolerance must match the lid tool. A good blow molder holds the mouth within a tight band so lids from any supplier fit. This fit is the practical meaning of leak-proof in daily use.
4. Resin Selection for Coating Buckets
Most 20 liter paint pails are made from high density polyethylene or polypropylene, with recycled content blended in for cost and sustainability goals. The resin choice sets the stiffness, the chemical resistance, the low temperature toughness, and the price per kilogram. Each plant balances these factors against the coating it packs.
| Resin type | Typical use in 20L pails | Stiffness and impact | Resin cost per kg (US dollars) |
|---|---|---|---|
| Virgin high density polyethylene | Standard paint and coating pails, good stiffness | High stiffness, medium low temperature impact | 1.10 to 1.50 |
| Virgin polypropylene | Hot fill or chemical resistant coatings | Good heat resistance, lower cold impact | 1.00 to 1.40 |
| Recycled high density polyethylene | Blended up to 30 percent for cost and eco goals | Slightly lower strength, needs cleaning | 0.70 to 1.00 |
| Color masterbatch and additive | Brand color, UV stabilizer, slip agent | Small dose, large appearance effect | 1.50 to 6.00 per kg of masterbatch |
Why high density polyethylene leads
High density polyethylene offers the best mix of rigidity and process speed for a 20 liter pail. It melts at a practical temperature, flows into the wide cavity, and releases cleanly. It resists the solvents and oils found in many coatings better than lower density options. For most paint plants, a high density polyethylene blend with a small recycled fraction is the default resin, and the machine is tuned around its melt behavior.
Polypropylene for heat and chemical resistance
When the coating is filled hot or contains aggressive solvents, polypropylene is the safer base. It tolerates higher temperature and many chemicals that would stress polyethylene. The trade is lower cold impact, so plants in cold climates may blend or choose a copolymer grade. The blow molder handles polypropylene with a slightly higher melt temperature and a careful cooling profile to avoid stress cracks at the handle.
Recycled content and contamination control
Blending recycled high density polyethylene lowers material cost and supports sustainability claims, but recycled flake can carry moisture, dust, and off spec melt. A dedicated machine pairs the hopper with a drying and filtration step and uses a screen pack at the head to catch grit that would otherwise mark the pail. A plant blending recycled content should budget for a cleaning and regrind system, which adds roughly 8,000 to 20,000 US dollars to the upstream line but pays back through resin savings.
Color and additive dosing
Brand color is added through a masterbatch dosed at 1 to 4 percent by weight. A gravimetric color feeder holds the dose within a tight band so a full production run stays one shade. Additives such as ultraviolet stabilizer protect pails stored outdoors, and a slip agent helps stacking release. The dosing channel and the purge path are part of a pail machine because color consistency is a daily quality issue, not an occasional one.
5. Whole Line Architecture and Key Components
A complete 20L paint bucket extrusion blow molding line contains more than the molder itself. The connected systems move resin in, form the pail, finish it, test it, and send it downstream. Understanding the full architecture helps a buyer budget the real project and avoid missing a component that blocks startup.
| Line component | Function | Typical price range (US dollars) |
|---|---|---|
| Resin silo and vacuum loader | Store and feed pellets to the hopper | 4,000 to 15,000 |
| Drying and blending unit | Remove moisture, mix recycled and color | 6,000 to 22,000 |
| Single screw extruder | Melt and homogenize the compound | 25,000 to 60,000 |
| Accumulator die head | Store melt, form wide mouth parison | 15,000 to 45,000 |
| Clamp and blow station | Close mold, inject air, hold pressure | 30,000 to 80,000 |
| Mold (20L bucket, single cavity) | Shape the pail and rim ledge | 8,000 to 25,000 |
| Deflashing and trimming unit | Remove flash, finish the lip | 6,000 to 18,000 |
| Leak tester and conveyor | Verify seal, move pails out | 8,000 to 22,000 |
| Chiller and cooling tower | Supply mold cooling water | 6,000 to 18,000 |
Turnkey line budget
A complete turnkey 20L paint pail line, from silo to leak tester, typically costs 120,000 to 380,000 US dollars depending on station count, cavity count, automation, and mold quality. A single station single cavity line sits at the low end. A double station double cavity line with robots and inline testing reaches the high end. The extruder and die head are the largest single cost, followed by the clamp and the mold.
6. Extrusion System and Barrier Screw
The extruder is the heart of the line. It receives solid pellets, melts them with shear and heater bands, mixes the color and recycled fraction, and pushes homogeneous melt into the accumulator head. For a 20 liter pail, the screw diameter usually falls between 60 and 90 millimeters, driven by the melt flow the parison demands.
Screw design for polyolefin pails
A three zone screw with a deep feed, a compressing transition, and a mixing metered end gives stable output for high density polyethylene and polypropylene. A barrier section near the melting zone separates solid and melt so no unmelted pellet reaches the head, which would otherwise cause a weak spot in the pail wall. A plant running recycled content benefits from a hardened screw and barrel because grit wears the metal over time.
Output and melt temperature
The extruder must deliver enough melt to fill a 20 liter parison within the cycle. A typical 20L pail uses 900 to 1,400 grams of resin, and the parison must be ready before the mold closes again. Melt temperature for high density polyethylene runs about 180 to 230 C, and for polypropylene about 200 to 250 C. Holding that window steady keeps the parison soft enough to blow yet firm enough to hold its wide shape.
Drive and energy
The extruder drive is a variable speed motor sized for the screw, usually 30 to 75 kilowatts for this class. A modern inverter drive trims energy by matching speed to demand. Across a year, the extruder is the largest steady power user on the line, so an efficient screw and motor combination saves thousands of US dollars in electricity. Wanplas configures the drive to the screw and resin so the plant does not overpay for unused capacity.
7. Accumulator Die Head with Wide Mouth Design
The die head is the most distinctive part of a 20L paint bucket machine. Because the parison is large and the mouth is wide, the melt is accumulated in a chamber and then pushed out as one piece rather than extruded continuously. This accumulator method keeps the parison temperature even and the wall balanced around the full circle.
How the accumulator works
Melt from the extruder fills a cylindrical accumulator behind the die. When the mold closes, a piston or ram pushes the stored melt out through the wide annulus, forming a parison that drops into the open mold. Because the whole parison is delivered at once, there is no thin neck from slow extrusion, and the wide mouth forms cleanly. After the shot, the accumulator refills during cooling, hiding the refill time inside the cycle.
Wide mouth mandrel and die gap
The mandrel sets the inside diameter of the parison, and the die ring sets the outside. For a wide mouth pail, both are large and must be centered so the wall is the same thickness on every side. A slight off center condition produces a thin spot that leaks or a thick spot that wastes resin. The head is built with adjustable bolts and a heating zone per segment so the operator can balance flow after a tool change.
8. Parison Control and Wall Thickness Uniformity
A paint pail must be thin enough to be cheap and thick enough to be strong, and the thickness must land in the right place. Parison control is the system that varies the die gap and the extrusion speed during the parison drop so the wall is programmed along the length of the part.
Why programmed wall thickness matters
Without control, the parison sags and the bottom of the pail ends up thin while the top is thick, or vice versa. A leak-proof pail needs extra wall at the bottom weld and the handle boss and lean wall on the straight side. A parison programmer sets dozens of points along the drop, opening the die slightly where more material is wanted and closing it where less is needed. The result is a pail that meets strength with the least resin.
Programmer hardware and cost
The programmer is a controller with servo or hydraulic actuators on the die bolts. A basic 20 to 40 point unit costs about 5,000 to 12,000 US dollars. A higher resolution unit with more points and faster response costs 12,000 to 20,000 US dollars. For a 20L pail where material is the largest recurring cost, the programmer usually pays for itself in resin saving within months, so it is rarely worth skipping.
Measuring and tuning the wall
The operator molds a few pails, cuts them, and measures wall at the base, the side, the shoulder, and the rim with a gauge. The readings feed adjustments to the programmer until the profile matches the target. A plant that documents the profile for each product can reload it on the next run, turning setup from guesswork into a saved recipe. Wanplas supplies the control software that stores these profiles by product code.
Avoiding thin spots that leak
Most leaks trace to a thin section at the bottom weld or a void at the handle. Parison control places resin exactly at those zones, and the clamp pressure then fuses them. When a pail fails a leak test, the first check is the wall map at the failure point, not the blow pressure. Getting the wall right upstream removes most leak problems before they reach the test station.
9. Blow Molding Clamp and Wide Mouth Mold
The mold is the cavity that defines the pail shape, and the clamp is the force that holds it shut against blow pressure. For a wide mouth 20 liter part, both must be robust and precise.
Clamp force and platen size
Blow pressure is modest compared with injection molding, but the projected area of a 20L pail is large, so the clamp still needs meaningful force, often 40 to 120 tons depending on cavity count. The platen must be wide enough for the open top and tall enough for the pail plus the neck ring. A double station machine carries two platens and alternates them so one cools while the other fills.
Mold material and cooling channels
A 20L pail mold is usually aluminum for faster cooling and lower cost, or steel for longer life on very high volume. Aluminum molds cost 8,000 to 18,000 US dollars and cool quickly. Steel molds cost 15,000 to 30,000 US dollars and last for millions of cycles. The mold carries internal channels that carry cooling water through the wall and the base, because the base is the thickest section and the last to set.
Forming the wide mouth and rim
The top of the mold includes a neck ring that shapes the wide mouth and the rim ledge in one blow. The ring must be machined to a tight circle so the lid seats evenly. A worn or misaligned ring produces an oval mouth that leaks, so the mold maker checks roundness during manufacture and the operator checks it during setup. Because the rim is formed, not cut, there is no trimmed edge to leak.
10. Cooling, Deflashing, and Trimming
After the pail is blown, it must cool, lose its flash, and reach the test station clean. These finishing steps decide the daily throughput and the surface quality.
Cooling the thick sections
The base and handle are the last parts to solidify, and if the pail is ejected too early it warps. The mold cooling water is chilled to about 10 to 18 C and circulated at enough flow to pull heat from the base. Cooling time is a large part of the cycle for a 20L pail, often 20 to 50 seconds per cavity. Speeding cooling with better water flow or a secondary air cooling tunnel can lift output without changing the molder.
Deflashing the parting line
Blow molding leaves a thin web of flash at the parting line where the two mold halves meet. A deflash station trims this web with a knife or a router and can also finish the top lip. Manual deflash is possible at low volume but slows the line and risks uneven edges. An automated deflash unit costs 6,000 to 18,000 US dollars and keeps the lip consistent so the lid fits every time.
Scrap recovery
Flash and reject pails are ground and, if clean, blended back into the resin stream at a controlled ratio. A granulator for this scrap costs 3,000 to 9,000 US dollars. Recycling the flash on site turns a waste stream into saved resin, and a plant that closes this loop can cut material cost by several percent. The regrind must be screened and dried before return so it does not introduce grit into the pail wall.
11. Leak-Proof Testing and Quality Control
Leak-proof is a claim that must be proven on every pail, not just on a sample. A coating plant cannot afford a pail that weeps on the shelf, so the line includes testing and inspection built into the flow.
Inline leak testing
An inline leak tester fills or pressurizes the pail with air and checks for pressure drop over a few seconds. A pail that holds pressure passes; one that drops fails and is ejected. A single station tester costs 4,000 to 12,000 US dollars and adds only a few seconds to the flow. For paint and coating, this test is the final guard against returns and is worth the footprint it occupies.
Wall map and dimensional checks
Periodic wall measurement confirms the parison program is still on target after a color change or a shift handover. Dimensional checks confirm the mouth diameter, the base diameter, and the height stay within the lid fit band. A plant records these numbers in a log so a drift is caught before a whole pallet is made out of spec. Wanplas configures the control system to flag out of range values automatically.
12. Process Parameters and Tuning
The machine runs on a set of linked parameters. Tuning them is how a plant reaches target weight, cycle time, and leak performance at the lowest cost.
| Parameter | Typical range for 20L pail | Effect on the part |
|---|---|---|
| Melt temperature | 180 to 250 C by resin | Sets parison softness and weld strength |
| Blow pressure | 6 to 12 bar | Pushes melt to the cavity detail |
| Blow time | 2 to 6 seconds | Holds shape before cooling |
| Cooling time | 20 to 50 seconds per cavity | Sets cycle and warp risk |
| Parison weight | 900 to 1,400 grams | Direct material cost per pail |
| Clamp force | 40 to 120 tons | Keeps mold shut under blow |
Tuning for lowest weight
The largest saving on a pail line is parison weight. Every gram removed from a pail that still passes leak and drop tests is pure margin across millions of units. Tuning starts with the parison program, then adjusts melt temperature so the wall fuses at the weld, then shortens cooling to the safe minimum. A plant that reviews weight weekly usually finds a few grams to remove without hurting quality.
Tuning for leak performance
Leak tuning begins at the weld. If leaks appear, raise the pinch temperature slightly, increase clamp force at the bottom, or add a little parison weight at the base. Changing blow pressure alone rarely fixes a leak because the issue is usually wall at the seam, not air pressure. A disciplined tuning order avoids chasing the wrong variable and wasting resin on over thick parts.
13. Capacity, Utilities, and Operating Cost
A buyer needs the real economics: how many pails per hour, what the line draws in power and water, and what each pail costs to make. These numbers decide payback and whether the machine fits the plant.
Hourly and yearly output
A single station single cavity 20L pail line at a 40 second cycle makes about 90 pails per hour, or roughly 2,000 pails per 22 hour day. A double station double cavity line at a 35 second cycle makes roughly 400 pails per hour, or about 8,800 per day. Most plants run the line 20 to 22 hours per day across two shifts, so yearly output ranges from about 600,000 to 2,500,000 pails depending on configuration.
Power, water, and air
The line draws about 60 to 140 kilowatts at full run, led by the extruder and the chiller. Cooling water circulates through the chiller and may need a cooling tower in hot climates, adding 5,000 to 15,000 US dollars for the tower. Compressed air for blowing and actuators runs about 0.5 to 1.5 cubic meters per minute. A plant should size the electrical supply and the compressor before delivery to avoid a bottleneck that caps output.
Cost per pail breakdown
For a high density polyethylene pail of 1,100 grams at 1.25 US dollars per kilogram, resin is about 1.38 US dollars. Color masterbatch at 3 percent adds roughly 0.04 US dollars. Energy at about 0.6 kilowatt hour per pail at 0.10 US dollars per kilowatt hour adds 0.06 US dollars. Labor and overhead add 0.10 to 0.25 US dollars, and mold amortization adds a few cents. Total variable cost lands near 1.60 to 2.00 US dollars per empty pail, before the lid and label.
Payback and margin
A turnkey line at 200,000 US dollars making 1,500,000 pails per year at a saving of even 0.05 US dollars per pail against bought in pails returns 75,000 US dollars per year, paying back in under three years, and that ignores the brand control of making one’s own packaging. For a coating plant with steady volume, in house pail production is usually the stronger economic choice. Wanplas sizes the line to the plant’s actual volume so the buyer does not pay for idle capacity.
14. Wanplas Machine Recommendations and Support
Wanplas supplies the full range of equipment for a 20L paint bucket extrusion blow molding project, from the resin handling at the start to the leak tester at the end. Because the group builds both the blow molder and the upstream compound machines, a plant can standardize on one engineering team and one spare parts list.
Recommended machine families
For the pail line itself, Wanplas offers single screw extrusion blow molding machines in the 60 to 90 millimeter screw range with single or double station clamps and accumulator heads sized for 20 liter wide mouth parts. For plants that blend their own compound, Wanplas supplies high speed mixers, gravimetric blenders, and screen changers that feed clean melt to the hopper. For recycled content programs, Wanplas provides granulators and washing lines that return flash and reject pails to the resin stream. Each family is built to the same control platform so operators move between machines with little retraining.
Mold and head options
Wanplas delivers aluminum and steel molds for 20L pails with the wide mouth neck ring and the reinforcement ribs engineered for the target resin. The accumulator die head is offered in single layer and three layer versions so a plant can choose recycled core construction when cost targets demand it. Because the head and mold are made to match the machine, the startup is faster and the wall program is easier to tune.
Service and support commitments
Wanplas runs continuous running tests before shipment so the unit arriving at the plant is already proven. The group offers on site commissioning, operator training, and remote diagnostics that let an engineer review the control screen from a distance and suggest a fix without a long travel delay. Spare parts are stocked so a worn screw or a damaged die bolt ships quickly, and a service plan that includes about 500 US dollars per year of free consumable parts keeps routine maintenance affordable.
Building a complete development unit
A plant starting fresh can work with Wanplas to build a complete line: silo and loader, dryer and blender, extruder, accumulator head, clamp with mold, deflash unit, leak tester, chiller, and conveyor, all commissioned as one project. This single supplier route reduces interface risk because one team is accountable for the whole cell. For a coating brand that values leak-proof consistency and a clean brand color, that accountability is often the deciding factor.
Scaling from trial to full volume
Wanplas also supplies smaller laboratory and pilot blow molding machines for plants that want to prove a new pail design before committing to a full line. A pilot machine lets the engineering team test a resin blend, a wall program, and a mold shape at low volume, then carry the saved recipe to the production machine. This staged path lowers the risk of a full investment and shortens the time from idea to shelf ready pail.
Frequently Asked Questions
What resin is best for a 20L paint pail?
High density polyethylene is the most common choice because it is stiff, processes quickly, and resists many coating solvents. Polypropylene is used when the product is hot filled or chemically aggressive. Recycled high density polyethylene is blended up to about 30 percent to lower cost, with cleaning and screening to protect quality.
How does the wide mouth stay leak-proof?
The wide mouth is formed by a neck ring in the mold rather than cut after molding, so there is no trimmed edge to leak. The rim ledge is machined to a tight circle so the lid gasket seats evenly, and the bottom weld is controlled by parison weight and clamp force at the seam.
What does a complete 20L pail line cost?
A turnkey line from silo to leak tester typically costs 120,000 to 380,000 US dollars depending on station count, cavity count, and automation. The extruder, accumulator head, and clamp are the largest cost items, followed by the mold and the leak tester.
How many pails can one machine make per hour?
A single station single cavity line at a 40 second cycle makes about 90 pails per hour. A double station double cavity line at a 35 second cycle makes roughly 400 pails per hour. Output scales with station count, cavity count, and cooling time.
Can recycled content be used in paint pails?
Yes, recycled high density polyethylene is commonly blended up to about 30 percent after cleaning and drying. A three layer head can place recycled content in the core and virgin material on the skin, keeping the surface clean while cutting resin cost.
Why is a parison programmer worth the cost?
The programmer varies wall thickness along the pail so resin lands where strength is needed and is removed where it is not. Because material is the largest recurring cost, the saving on parison weight usually recovers the 5,000 to 20,000 US dollars programmer cost within months.
What causes a pail to leak?
Most leaks trace to a thin wall at the bottom weld or a void at the handle boss, not to low blow pressure. Fixing them means adjusting the parison program, raising pinch temperature, or adding clamp force at the seam rather than raising air pressure.
How long does a pail mold last?
An aluminum mold lasts hundreds of thousands of cycles and suits moderate volume. A steel mold lasts millions of cycles and suits very high volume. The choice balances upfront cost against lifetime and cooling speed.
What utilities does the line need?
The line draws about 60 to 140 kilowatts, needs chilled water for the mold, and uses 0.5 to 1.5 cubic meters per minute of compressed air. A plant should size the electric supply, the chiller, and the compressor before delivery.
Does Wanplas supply the whole line?
Yes. Wanplas supplies the extruder, accumulator head, clamp and mold, deflash unit, leak tester, chiller, and upstream compound equipment, all on one control platform with one service team, so a plant can build and scale the cell as a single project.
Conclusion
A 20L paint bucket extrusion blow molding machine with a wide mouth leak-proof design is a focused production system built around two demands: a broad opening that stays round and a weld that never weeps. The accumulator die head forms the wide parison, the parison programmer places wall where the pail needs strength, the clamp and mold shape the rim and the handle, and the leak tester proves the result. With high density polyethylene or polypropylene, a tuned wall program, and disciplined cooling, a plant can make pails at a variable cost near 1.60 to 2.00 US dollars each while holding the lid fit and the seal that coating brands require.
Wanplas supports this project from resin handling through leak testing, with extrusion blow molding machines in the right screw range, aluminum and steel molds, single and three layer heads, and the upstream compound and recycling equipment that close the material loop. Backed by continuous running tests before shipment, on site commissioning, remote diagnostics, and a spare parts program, the Wanplas approach lets a coating plant bring pail production in house with confidence and scale from a single station to a double station cell as volume grows.
