Contents
1. What a PE Breathable Film Extrusion Line Is and Who Buys One
The product the line makes
The pores that make the film breathable are not holes punched by a needle. Water vapor molecules are small enough to diffuse through the same path, so the film behaves like a selective barrier rather than a sieve. Wanplas builds the stretching and heat setting sections with independent temperature zones so that a converter can move along that balance without changing the base sheet recipe.
Three buyer profiles and what each one needs
Each profile also has a different tolerance for downtime and a different view of what a spare parts inventory is worth. Wanplas recommends a small but deliberate spares package for every line and includes one free spare parts allowance of 500 US dollars per year on supplied equipment.
What the line does not do
The line also cannot compensate for a poorly made compound. This is why a serious project includes either a compounding step or a tightly specified purchased compound, and why incoming resin testing is not optional.
2. Backsheet Requirements for Diapers and Sanitary Napkins
Breathability and waterproofness as opposing targets
The physics behind the tradeoff is straightforward but unforgiving in production. Vapor transmission rises as the total void volume in the film rises, and void volume rises with filler loading, particle size and draw ratio. Wanplas includes correlation work between inline gauge readings and laboratory results during commissioning so that an operator can see a drift before it becomes a rejected pallet.
Mechanical demands during converting and wear
A backsheet must survive a converting line that pulls, folds, glue sprays, ultrasonically bonds and cuts it at 200 to 600 products per minute. Wanplas supplies a corona treater with a dyne verification kit and advises converters to retest dyne level on any roll older than fourteen days rather than assuming the treatment survived the warehouse.
How diaper backsheets differ from napkin backsheets
The commercial difference is just as large as the technical one. That is still far cheaper than two dedicated lines, which would double the capital and require a second crew.
3. PE Resin, Calcium Carbonate Masterbatch and Compound Cost
Resin blend design
Additives are a small fraction of the formula but a large fraction of the trouble. Processing aid based on fluoropolymer is sometimes used to suppress melt fracture at high output, but it costs 12,000 to 22,000 US dollars per ton and can interfere with corona treatment, so Wanplas generally solves die lip polish and temperature profile issues before recommending it.
Calcium carbonate filler and why it creates pores
Filler quality has a direct and measurable cost. That is why Wanplas recommends qualifying at least two filler suppliers with identical particle size specifications and keeping a two week buffer stock, especially for plants far from a port. A small dehumidified store room costing 12,000 to 35,000 US dollars is one of the highest return items in a hygiene film plant.
Compound cost and the make versus buy decision
The cash model for a purchased compound is easier to audit and easier to present to a lender. Wanplas helps buyers build a simple spreadsheet with resin price, filler price, power price, freight, yield and working capital so that the decision is made on their own numbers rather than on a supplier rule of thumb, and the same model is later reused to set a selling price for the finished film.
4. Cast Film, Blown Film and Why Stretching Creates Pores
Two routes to the filled base sheet
There is also a third route used for the cheapest products, in which a moderately filled cast film is sold without stretching and relies on a small amount of surface porosity for a modest vapor value of 200 to 600 grams per square meter over 24 hours. That upgrade path is worth planning for even when the first order book does not justify it. The decision between the three routes should be made from the target vapor transmission number, not from the cheapest machine quotation.
What happens inside the stretching gap
Two stage orientation is used when a producer wants high vapor transmission without destroying liquid barrier. Wanplas asks for the intended product mix at the quotation stage and will quote a single gap unit with a prepared second gap position if the buyer expects to move upmarket later.
Heat setting, shrinkage and roll stability
Roll building is the last part of the same problem. Roll hardness should be even across the width, and a soft center with hard edges is a reliable sign that the stretching gauge profile was crowned.
5. Complete Line Architecture and Equipment Price List
The web path from pellets to roll
Control architecture ties the sections together. Wanplas treats the recipe as a controlled document, so only a supervisor code can change a setpoint and every change is time stamped together with the roll number and the laboratory result.
Fifteen line items with realistic prices
The table below gives a mid range budget for a 1,600 millimeter cast and stretch line rated at 350 to 500 kilograms per hour, quoted in US dollars for equipment only. Prices assume a standard industrial finish, a 380 to 480 volt three phase supply and no building work.
| Equipment item | Main function on the line | Typical price in US dollars |
|---|---|---|
| Vacuum loader and drying hopper | Conveys pellets and holds masterbatch below 0.10 percent moisture | 18,000 to 48,000 |
| Loss in weight feeder set | Doses resin, filler masterbatch and additives within plus or minus 0.5 percent | 32,000 to 85,000 |
| Single screw extruder with barrier screw | Melts and homogenizes the filled compound at 350 to 500 kilograms per hour | 110,000 to 260,000 |
| Continuous screen changer | Removes gels and hard agglomerates without stopping the line | 22,000 to 58,000 |
| Melt pump and pressure loop | Holds die pressure within plus or minus 2 bar and steadies output | 38,000 to 90,000 |
| Coat hanger flat die with thermal lip bolts | Spreads melt to 1,600 millimeters and trims the base sheet profile | 95,000 to 240,000 |
| Chill roll unit with air knife and vacuum box | Quenches the base sheet and pins it flat without trapped air | 85,000 to 210,000 |
| Base sheet gauge and profile scanner | Measures incoming thickness before orientation and feeds die lip control | 48,000 to 130,000 |
| Preheat roll stack | Brings the web to 75 to 105 degrees C evenly across the width | 55,000 to 140,000 |
| Machine direction stretching unit | Draws the web 2.2 to 3.6 to 1 and opens the microvoids | 130,000 to 340,000 |
| Heat setting and cooling rolls | Locks the oriented structure and brings shrinkage below 3 percent | 70,000 to 175,000 |
| Corona treater with dyne kit | Raises surface energy to 36 to 42 dynes per centimeter for bonding and printing | 28,000 to 75,000 |
| Turret winder with tapered tension | Builds stable rolls and splices without stopping the line | 85,000 to 220,000 |
| Line control, recipe management and logging | Coordinates every drive, stores setpoints and issues roll reports | 55,000 to 160,000 |
| Installation, commissioning and training | Mechanical erection, first production run and operator certification | 45,000 to 130,000 |
Adding the mid points of those fifteen items gives roughly 0.92 million US dollars for the core line, and the realistic spread across the low and high columns is 0.62 to 1.75 million US dollars. Wanplas quotes each item separately so that a buyer can see exactly what a lower bid has removed, and will not delete the melt pump, the base sheet gauge or the heat setting rolls to reach a target price, because all three are what make a filled web stretchable at all.
Items that are frequently left out of a quotation
Qualification is the other invisible cost. Running those lots consumes 15 to 45 tons of compound worth 15,000 to 60,000 US dollars and occupies the line for three to eight days, and a failed attempt repeats the whole exercise.
6. Extruder, Screen Changer and Flat Die Design
Screw geometry for a heavily filled compound
Barrel temperature is set as a rising profile, typically 155 to 170 degrees C at the feed zone, 180 to 195 in compression, 195 to 210 in metering, and 200 to 210 at the adapter and die. Wanplas installs two melt temperature points and an alarm at 218 degrees C, and logs the value against each roll so that a customer complaint about odor can be checked against an actual thermal history rather than against an operator memory.
Filtration, melt pump and die lip control
Filtration is not a luxury on a stretching line, because one hard agglomerate above 30 micrometers can start a tear that runs the full web width in the gap. A gear pump sized for 500 kilograms per hour costs 38,000 to 90,000 US dollars and needs a rebuild every 20,000 to 35,000 hours at 9,000 to 22,000 US dollars.
7. Casting Roll, Air Knife and Base Sheet Gauge Control
Quenching a filled web without trapping air
Roll surface condition is a production variable, not a maintenance detail. Wanplas recommends keeping one spare casting roll for a two line plant and includes a roll surface log in the recipe sheet, so that a repeating defect can be matched to a roll number and a date. Wanplas includes grounding checks in the commissioning checklist and measures surface potential at the winder with a handheld meter costing 400 to 1,200 US dollars.
Measuring the base sheet before orientation
Everything that is wrong in the base sheet is magnified by the stretching gap, which is why a gauge station before the preheat rolls is worth its 48,000 to 130,000 US dollars. A combined two station package with profile display and roll reporting costs 95,000 to 240,000 US dollars, and Wanplas treats it as core equipment rather than as an option on any line selling into a branded hygiene program.
Gauge data is also the basis for the material balance that tells a plant its true yield. A daily reconciliation sheet takes ten minutes and can save 30,000 to 90,000 US dollars a year on a mid size line. Wanplas configures the line control to export feeder totals, line speed, finished gauge and roll weight to a single shift report, and recommends that the report be reviewed by a supervisor rather than filed automatically.
8. Machine Direction Orientation Hardware and Roll Drive
Roll construction, gap setting and drive accuracy
Temperature uniformity across a 1,600 millimeter roll is harder than it sounds. Wanplas measures the face temperature with a contact probe at nine points during commissioning and records the map, then repeats the check every six months because a partially blocked channel develops slowly.
Maintenance, spares and the real cost of a web break
Spares strategy for the orientation section should be deliberate. Wanplas keeps dimensional drawings and coating specifications on file for every supplied roll so that a replacement can be ordered by part number rather than by measurement, and includes a free spare parts allowance of 500 US dollars per year on supplied lines. A written log with the hours and the findings costs nothing and is one of the first documents a hygiene brand auditor asks to see.
9. Sixteen Process Parameters and the Cost of Deviation
Reading the parameter table as a control plan
The sixteen values below are a working baseline for a 1,600 millimeter cast and stretch line producing a 20 gram per square meter diaper backsheet from a 52 percent filled compound. The last column describes what happens when the value drifts out of range, which is the part of a parameter sheet that operators actually use. Wanplas issues a versioned recipe sheet in this form for every grade proven during the factory trial and trains the shift team to change one value at a time with a fifteen minute stabilization period before judging the result.
| Parameter | Baseline value and working range | Consequence of deviation |
|---|---|---|
| Compound moisture | Below 0.10 percent, alarm at 0.15 | Pinholes at the die and a rough surface that fails head testing |
| Feed zone temperature | 160 degrees C, range 155 to 170 | Surging and poor filler dispersion, visible as gauge ripple |
| Metering zone temperature | 202 degrees C, range 195 to 210 | High values degrade filler coating and cause odor complaints |
| Melt temperature at the adapter | 207 degrees C, alarm at 218 | Yellowing, gels and a narrow stretching window |
| Melt pressure before the die | 16 to 22 megapascals, held within 2 bar | Output pulsation that becomes a vapor transmission ripple |
| Screw speed | 45 to 110 revolutions per minute | Excess shear heat and filler breakdown at the flight tips |
| Screen pack rating | 40 to 80 micrometers | Coarse filtration allows agglomerates that start web tears |
| Die gap | 0.6 to 1.2 millimeters | Too narrow raises pressure; too wide hurts profile control |
| Chill roll temperature | 40 degrees C, range 25 to 60, plus or minus 1 | Trapped air and haze when cold, roll marks when warm |
| Base sheet gauge | 85 micrometers, plus or minus 3 percent | Any ripple is magnified threefold by the draw |
| Preheat roll temperature | 92 degrees C, range 75 to 105, face plus or minus 1 | Cold web tears at particles, hot web relaxes before voids form |
| Draw ratio | 2.8 to 1, adjustable 2.2 to 3.6 | High draw raises vapor transmission but cuts hydrostatic head |
| Stretching gap | 5 millimeters, range 2 to 12 | Wide gap gives uneven draw and edge necking |
| Heat setting temperature | 115 degrees C, range 105 to 125 | Low values leave shrinkage above 6 percent and cause curl |
| Corona power density | Set to reach 38 to 40 dynes per centimeter | Over treatment makes film brittle, under treatment loses bonding |
| Winding tension | 35 newtons per meter, tapered down 20 percent | High tension crushes voids and telescopes rolls |
The table also shows why a recipe should never be edited by an operator trying to fix a single laboratory result. Wanplas recommends a written decision tree for the four most common deviations in vapor transmission, head, gauge and shrinkage, with one allowed adjustment per step and a fifteen minute wait before the next measurement. A plant that tries to compress that into twenty minutes usually pays for it with a full roll of off grade film.
10. Corona Treatment, Printing, Slitting and Winding
Surface energy, printing and the bonding window
A filled polyethylene film leaves the heat setting rolls with a surface energy near 30 dynes per centimeter, which is too low for reliable hot melt bonding or water based ink adhesion. Wanplas recommends treating to the lower end of the customer window and recording the value on the roll label, with a retest instruction for any roll older than fourteen days.
Slitting, roll packaging and traceability
Every slit roll should carry a label that links it back to the jumbo roll, the compound lot, the shift, the recipe version and the laboratory results, because a hygiene brand audit will follow that chain. Wanplas supplies a roll map template and a written packaging instruction as part of commissioning, and recommends a first in first out warehouse rule so that corona dyne decay never surprises a converting shift.
11. Quality Control, Breathability Testing and a Testing Cost Table
What a release test must cover
Testing frequency should follow risk rather than habit. Vapor transmission and head are checked on every jumbo roll because they depend on the stretching section and drift with temperature. Gauge and tensile are checked every roll but with fewer replicate samples. That ratio is why Wanplas argues for a laboratory sized to the line rather than to the budget, and why it includes breathability correlation work during factory trials to establish what inline gauge and temperature readings predict about the laboratory result.
Fourteen test items and their annual cost
The table below estimates the annual cost of a quality system for a single 1,600 millimeter line producing about 2,400 tons a year. Equipment figures are amortized over five years, and labor covers two technicians per shift on a three shift rotation. Figures are in US dollars.
| Test or control item | Frequency and method | Equipment and annual cost in US dollars |
|---|---|---|
| Water vapor transmission | Three points per roll, cup method over 24 hours | 4,000 to 11,000 equipment, 8,000 to 20,000 per year |
| Hydrostatic head | Three points per roll, rising water column | 6,000 to 18,000 equipment, 5,000 to 14,000 per year |
| Mass per unit area | Every roll, five cut and weigh samples | Inline gauge plus 1,500 to 4,000 balance, 3,000 to 8,000 per year |
| Tensile and elongation | Every roll, both directions, five strips each | 14,000 to 38,000 frame, 6,000 to 15,000 per year |
| Transverse tear strength | Every roll, pendulum or trouser tear | 3,000 to 9,000 equipment, 2,000 to 6,000 per year |
| Residual shrinkage | Every roll, 10 minutes at 100 degrees C | 1,500 to 5,000 oven, 2,000 to 5,000 per year |
| Corona dyne level | Start and end of every roll, dyne solutions | 300 to 900 kit, 2,000 to 6,000 per year in fluids |
| Coefficient of friction | Once per shift against a standard sled | 4,000 to 11,000 equipment, 2,000 to 5,000 per year |
| Hot melt peel strength | Once per shift on a bonded laminate sample | Uses tensile frame, 3,000 to 8,000 per year in adhesive |
| Gel and agglomerate count | Each incoming compound lot, pressed plaque and microscope | 3,000 to 9,000 microscope, 3,000 to 9,000 per year |
| Compound moisture | Every lot and every opened bag after a humid shift | 2,000 to 6,000 balance, 2,000 to 5,000 per year |
| Instrument calibration | Annual, plus check samples each month | 6,000 to 18,000 per year |
| External migration and skin contact testing | On grade change or customer request, outsourced | 12,000 to 45,000 per year, 400 to 1,500 per batch |
| Laboratory staff, samples and records | Two technicians per shift and a day supervisor | 90,000 to 230,000 per year |
Adding those fourteen items gives an annual quality bill of roughly 145,000 to 400,000 US dollars, or 0.06 to 0.17 US dollars per kilogram of film, with the laboratory itself costing 45,000 to 140,000 to equip. Wanplas recommends treating the laboratory as a production department with its own shift handover and its own calibration calendar, and includes a two day training module on the four barrier and mechanical tests with every line.
12. Plant Layout, Utilities, Safety and Staffing
Building, power and water
Water and air are smaller but easy to under specify. A compressor, dryer and receiver cost 12,000 to 35,000 US dollars. Wanplas supplies a utility schedule with flow rates, connection sizes and heat rejection figures early in a project, because a chiller ordered after the line arrives is the most common reason a commissioning date slips by four to eight weeks.
Safety, housekeeping and crew size
A three shift single line plant typically employs four to six people per shift: one line operator, one assistant on the winder and slitter, one laboratory technician, one material handler and a shift supervisor, with maintenance and warehouse support on the day shift. Wanplas provides operator training at commissioning, a written recipe book and remote diagnostics, and recommends a quarterly refresher built around one actual near miss from the plant’s own log rather than a generic safety video. A crew that understands why a 4 degree C roll face difference produces a breathability stripe will protect the equipment better than any alarm setpoint.
13. Cost per Square Meter and Market Price Benchmarks
Building the cost model from the line upward
The cleanest way to price a breathable backsheet is per square meter, because the customer buys area, not weight. At a purchased compound price of 1,100 US dollars per ton, the material alone is therefore 0.023 to 0.025 US dollars per square meter.
Twelve line items in the square meter cost
The table below is a worked example for a 20 gram per square meter diaper backsheet on one 1,600 millimeter line at 2,400 tons a year, with all figures in US dollars per square meter. Low and high columns reflect a well optimized plant and a plant still climbing the learning curve.
| Cost item | Basis of the estimate | US dollars per square meter |
|---|---|---|
| Filled compound | 20 grams per square meter, 900 to 1,350 per ton, 44 to 47 square meter yield | 0.020 to 0.031 |
| Trim, break and start up losses | 8 to 14 percent of material, partly recovered as regrind | 0.002 to 0.005 |
| Electricity and chilled water | 0.45 to 0.85 kilowatt hours per kilogram, 0.08 to 0.16 per unit | 0.001 to 0.003 |
| Direct labor | Four to six people per shift, three shifts | 0.002 to 0.006 |
| Ink, corona and adhesive consumables | Only on printed grades, 1.2 to 2.5 grams of ink per square meter | 0.000 to 0.004 |
| Cores, wrap, labels and pallets | Slit roll packaging and moisture barrier | 0.001 to 0.003 |
| Screens, knives and spare parts | 60 to 180 screen sets a year plus roll and knife replacements | 0.001 to 0.003 |
| Laboratory and quality | 145,000 to 400,000 per year spread over annual area | 0.001 to 0.004 |
| Cash conversion cost | Sum of the eight lines above | 0.029 to 0.043 |
| Depreciation and financing | 1.0 to 2.4 million project over eight years, 6 to 10 percent interest | 0.005 to 0.012 |
| Indirect overhead and insurance | Supervision, warehouse, administration, freight to customer | 0.003 to 0.010 |
| Fully absorbed cost and selling price | Total cost 0.038 to 0.058, qualified grade sells at 0.055 to 0.095 | Margin 0.015 to 0.045 |
Three levers dominate this model. The second is compound price, where in house compounding saves 180 to 410 US dollars per ton, or 0.004 to 0.009 per square meter. Wanplas recommends modeling all three scenarios before signing a purchase order, and will adjust the line width and stretching configuration so that the capital matches the contracted volume rather than an optimistic forecast.
14. Investment, Payback and Wanplas Equipment Recommendations
Three investment tiers and what each one buys
The upper tier is a 2,000 to 2,400 millimeter line at 600 to 900 kilograms per hour with two stage stretching, inline printing, automatic slit width change and a full plant wide data system. Wanplas advises buyers to phase the upper tier: install one wide line with a prepared second bay, qualify the customer, then add the second line when contracted volume passes 75 percent of the first line’s practical capacity.
Payback worked through on a middle tier project
Cash flow timing deserves its own paragraph, because a new hygiene film plant spends heavily before it earns anything. Interest during construction, freight, duties, insurance and a contingency of 8 to 12 percent should all be in the project number. Wanplas helps buyers prepare the technical part of a toll proposal, including a realistic yield curve for the first six months, because a conversion fee agreed against nameplate output rather than against a learning curve is a reliable way to lose money while looking busy.
Wanplas equipment families and the services around them
Wanplas supplies the equipment families that make up a breathable film line: single screw extruders sized for filled compounds, twin screw compounding lines for producers who make their own filled pellets, vacuum loaders and loss in weight feeders, continuous screen changers and melt pumps, coat hanger flat dies with thermal lip adjustment, chill roll casting units with air knife and vacuum pinning, base sheet and finished film gauge scanners, single and two stage machine direction orientation units, heat setting and cooling roll stacks, corona treaters, inline flexo printing stations, turret winders, slitter rewinders, trim recovery granulators and the line control system that ties them together. Wanplas also supplies cast film lines without a stretching section for producers making non breathable backsheets, and blown film lines for customers who prefer balanced mechanical properties.
Services matter as much as the hardware on a process this sensitive. Wanplas runs formulation trials with the customer’s own compound on the actual stretching unit before shipment, so that a material which casts well but tears at a 3.2 to 1 draw is identified in the factory rather than after installation. Wanplas recommends that a buyer attend the factory trial in person with the person who will run the line, because the questions asked during a trial about roll cleaning, gap setting and web break recovery are the ones that save the most production hours later.
Frequently Asked Questions
What is the smallest practical line for a new hygiene film business?
A 600 to 1,000 millimeter cast and stretch line at 80 to 180 kilograms per hour is the smallest configuration that can produce a genuinely breathable film, and equipment for it costs 0.22 to 0.48 million US dollars. Below that width the stretching rolls become difficult to heat evenly and the saleable area per roll is too small to interest a converter, so buyers are usually better served by a non breathable cast line. A full project including utilities, a small laboratory and qualification material lands at 0.40 to 0.85 million US dollars.
Can one line make film for both diapers and sanitary napkins?
Yes, provided the stretching unit has a draw ratio range of at least 2.2 to 3.6 to 1 and the heat setting section has independent temperature zones, because diaper grades need higher vapor transmission while napkin grades need higher hydrostatic head and lower shrinkage. Each grade change takes 45 to 90 minutes and consumes 200 to 600 kilograms of start up material worth 200 to 800 US dollars. A plant serving both markets should expect 8 to 15 percent of calendar time lost to changeovers and should hold separate versioned recipes for each family.
Is it necessary to compound the filled material in house?
Not at the beginning. Purchased breathable film compound costs 900 to 1,350 US dollars per ton and removes the need for a 0.28 to 0.75 million US dollar twin screw compounding line, a formulation chemist and a dispersion test routine. In house compounding saves 180 to 410 US dollars per ton in cash terms, which becomes meaningful above roughly 1,500 to 2,000 tons a year. Wanplas generally advises buying compound for the first twelve to eighteen months, then adding compounding once the film line is stable and volume is contracted.
Why does the film lose waterproofness when breathability is increased?
Both properties come from the same microvoids. Raising filler loading, particle size or draw ratio increases total void volume, which lets more water vapor diffuse through, but it also enlarges the biggest connected pores, and liquid water under pressure crosses those first. A two stage stretching unit produces smaller and more uniform voids, so it can hold 150 centimeters of hydrostatic head at vapor values where a single stage unit has already fallen below 90 centimeters. The addition costs 0.16 to 0.40 million US dollars and is justified mostly by premium diaper and adult care programs.
What causes most web breaks in the stretching gap?
Three causes account for the majority: a hard agglomerate in the compound above 10 micrometers, a cold spot of 3 to 6 degrees C on a preheat roll, and a draw ratio set too close to the tear limit of that particular lot. Incoming dispersion testing with a 3,000 to 9,000 US dollar microscope, a nine point roll face temperature map and a documented maximum draw ratio per recipe address all three. A quick release roll gap costing 8,000 to 22,000 US dollars prevents a break from wrapping hot film around the rolls and turning a ten minute event into a two hour cleaning job.
How long does customer qualification take and what does it cost?
A hygiene brand normally asks for three consecutive lots that meet the full specification, a documented change control procedure, a traceable roll map and often a plant audit, so three to eight days of line time and 15 to 45 tons of compound worth 15,000 to 60,000 US dollars are typical. Export programs may add 12,000 to 45,000 US dollars for third party migration and skin contact testing. Wanplas recommends reserving 12 to 18 percent of total project capital for qualification, laboratory equipment and first fill material, because these costs rarely appear in an equipment quotation.
How much floor space and power does a middle tier line need?
The line itself needs a clear bay of 34 to 46 meters by 9 to 14 meters with 5.5 to 7 meters of height, and a realistic single line plant including storage, laboratory, slitting and warehouse occupies 1,400 to 2,600 square meters. Installed power is 320 to 620 kilowatts, with chilled water at 30 to 90 cubic meters per hour and compressed air at 1.5 to 4 cubic meters per minute. A 5 to 10 ton overhead crane costing 25,000 to 70,000 US dollars is needed because a 1,600 millimeter chrome roll weighs 700 to 1,800 kilograms.
What is a realistic first year yield for a new plant?
A new plant should plan for 78 to 88 percent first grade output in year one and target 90 to 94 percent once recipes are stable and the crew has twelve months of experience, rather than budgeting against a supplier’s nameplate figure. Start up scrap, grade changes, web breaks and off specification vapor transmission are the main losses, and together they typically consume 8 to 14 percent of material. A 10 point improvement in saleable yield cuts fully absorbed cost by 0.005 to 0.008 US dollars per square meter, which on a middle tier plant is worth 550,000 to 880,000 US dollars a year.
Conclusion
A PE breathable film extrusion line for a diaper or sanitary napkin backsheet is best understood as a pore engineering process rather than as a film casting process, because the extruder, the die and the chill roll only make a filled base sheet while the stretching and heat setting section is what turns that sheet into a selective barrier. The vapor transmission value and the hydrostatic head that a hygiene brand buys are set by filler loading, particle size, draw ratio and setting temperature, and every one of those is a line setpoint that drifts with roll temperature, gauge and compound quality. That is why the instrumentation, the gauge stations and the versioned recipe book are not optional extras, and why a line purchased on the strength of its extruder alone will spend its first year making off grade rolls that look perfect to the eye.
The commercial case rests on the same discipline. A middle tier project of roughly 1.45 million US dollars can return its equipment cost in 18 to 30 months at 82 percent first grade yield, 6,000 running hours and a qualified selling price near 3.60 US dollars per kilogram, but the same machine at 70 percent yield and 4,800 hours stretches payback beyond four years. Yield, utilization and an anchor customer matter more than a small saving on the purchase price, and the working capital needed to survive a four to seven month delivery plus three to six months of qualification is as important as the line itself. A producer who models filler cost, saleable area per kilogram, trim recovery, energy and laboratory effort against its own resin and power prices will make a better decision than one who compares two equipment quotations side by side.
Wanplas supplies the full family of equipment for this process, from compounding and extrusion through casting, single or two stage machine direction orientation, heat setting, corona treatment, printing, winding and slitting, along with factory trials using the customer’s own compound, layout and utility drawings, installation and commissioning, operator training, remote diagnostics and spare parts support. The most useful next step is to write down the target vapor transmission, hydrostatic head, grams per square meter, finished width, annual tonnage, local resin and power prices, and the two or three grades that will carry most of the volume, so that a configuration and a budget can be built around real operating conditions. A factory trial with the actual compound then confirms the stretching window before any equipment decision is finalized, and that single step is the least expensive insurance a buyer can purchase against a line that never quite reaches its nameplate output.
