Film Blowing and Nylon Extrusion Lines

An extruder is rated in kilogrammes per hour. You sell bags. Those two facts pull apart the moment the legal thickness changes, and that is the whole problem with buying one right now.

Description

A film blowing line melts polyethylene granules, forces the melt through an annular die, and inflates it into a bubble that is cooled, flattened and wound onto a roll. What comes off the winder is film. Turning film into bags is a separate machine, and buyers regularly budget for the first and forget the second.

The line makes shopping bags, refuse sacks, sachet water film, industrial liners and packaging rolls, and it will make all of them badly if the gauge control is poor. Consistency across the web is the difference between a roll you can sell and a roll where part of every metre is out of specification.

We source both single layer and co-extrusion lines, from manufacturers rather than trading companies, because on this class of machine the difference in after-sales is large.

Specification

These are the parameters that decide the right line. Figures are confirmed against the specific model and against written supplier data before we quote.

Screw diameter	The single most consequential number, because it sets the output ceiling and cannot be changed afterwards. Specify it against the thickest film you may be required to run.
Output in kg/hr	Ask for it separately for HDPE and LDPE. They differ on the same machine, and a single headline figure usually quotes whichever is higher.
Lay-flat width	Sets the largest bag you can make. Like the screw, it is fixed at purchase, so buy width you do not need yet rather than width you will grow out of.
Thickness range and tolerance	Both figures, in writing. A line set to 40 microns that swings between 34 and 46 averages 40 and still puts illegal film in every roll, and you cannot tell which part.
Gauge control	Oscillating haul-off, internal bubble cooling, automatic gauge control. This is what holds the tolerance, and it is where cheap lines save their money.
Die head	Quality here shows up as consistency across the web rather than as anything visible in a demonstration.
Chiller and air compressor	Frequently left out of the quotation and then discovered at commissioning. Confirm in writing whether they are included.
Total connected load	In kW for the whole line. This sizes the generator, and on a continuously running extruder the generator is the largest line in your running cost.
Bag making machine	Separate from the extruder. Side seal, bottom seal or t-shirt vest, decided by what you are actually selling.

We do not publish prices, because the landed figure depends on the specification, the Customs valuation and the exchange rate on the day you pay.

Minimum order

One line. No minimum applies to production machinery. A single extruder with a bag machine is a normal order.

Resin is where minimums bite, and it is usually sold by the tonne or by the container. If you want us to source granules alongside the machine we will get the supplier's actual minimum in writing and show it in the quotation.

Lead time is manufacture plus shipping plus clearing. We give a range on each rather than a single date.

What decides the right one

Gauge control, ahead of output. A fast line that cannot hold thickness is a line producing rolls you cannot legally sell in Lagos, and the fine there runs to ₦250,000 or three months' imprisonment. Output you can sell beats output you cannot.

Then honest capacity. Brochure output assumes a machine that never stops, an operator who never errs and power that never dips. Sizing on that figure is how factories end up with capacity they pay for and do not use, which we have written about at length elsewhere on this site.

Then spares. Heater bands, screws and die components wear. Ask what is held in Nigeria before choosing a brand, because a four month wait for a part is four months of a stopped factory.

Common questions

What is the minimum order?

One line. No minimum applies to production machinery, so a single extruder with a bag machine is a normal order.

Why does thickness tolerance matter more than speed?

Because film below the legal gauge cannot be sold. A line set to 40 microns that swings between 34 and 46 averages 40 and still puts illegal film in every roll.

What happens if the film comes out under thickness?

In Lagos the fine runs to 250,000 naira or three months' imprisonment. A fast line that cannot hold thickness is a line producing rolls you cannot legally sell.

Which specification cannot be changed afterwards?

The screw diameter. It sets the output ceiling of the line, and it is not something you can revisit once the machine is built.

Tell us what you intend to make and at what thickness

Bag size, film gauge, and the tonnage you expect to run in a month. We will tell you what screw diameter and lay-flat width that requires, what the line lands at in Naira with every line itemised, and what your cost per bag works out at on current resin prices.

There is no charge for it and it commits you to nothing. If the capacity you have in mind is larger than your market will absorb, we will tell you that before you order rather than afterwards.

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