Machines Required to Start a Plastic Bag Production Factory in Nigeria

The previous article ended on a claim worth taking seriously. Holding 40 microns consistently, which is what selling legally into Lagos now requires, is decided by the machine you buy rather than by how carefully you run it.

This is where that gets settled. Not a shopping list, but the numbers to ask for and what each of them will mean on your factory floor two years from now.

The film blowing line

This is the machine that matters. Resin goes in as granules, comes out as a tube of film, and everything downstream only cuts and prints what this line produced. A weak extruder cannot be corrected later.

Four figures describe it, and a quotation that omits any of them is not a quotation yet.

Screw diameter, given in millimetres. It sets the output ceiling. As a rough guide, a 45mm screw runs somewhere around 35 to 50 kg an hour, a 50mm around 50 to 70, a 55mm around 70 to 90, and a 65mm well past 100. Treat those as indicative and make the supplier state his own figure.

Output in kilograms per hour, stated separately for HDPE and LDPE, because they do not run the same. One Chinese line we have seen quoted lists 120 kg/hr on HDPE and 150 kg/hr on LDPE from identical screws. If a supplier gives you one number without saying which resin it refers to, he has given you the flattering one.

Lay-flat width in millimetres, which caps the largest bag you can make. Buying narrow to save money is the decision most first factories regret, because the customer who arrives two years later with a large-format order is the one you wanted.

Thickness range. Ordinary lines cover roughly 6 to 100 microns, so 40 is comfortably inside the capability of almost anything on the market. Capability is not the question. Consistency is.

Gauge control, the specification nobody asks about

A line set to 40 microns does not produce 40 microns across the whole web. It varies, and the variation is what decides whether your bags pass.

If your film swings between 34 and 46 to average out at 40, part of every roll is below the legal threshold in Lagos, and you have no way of knowing which part. That is the difference between a factory with a market and a factory with a warehouse of stock.

Three things control it. An oscillating or rotating haul-off distributes thickness variation across the roll instead of letting it build in the same place. Internal bubble cooling stabilises the bubble and lets you run faster without losing control of the gauge. Automatic gauge control, where the die adjusts itself, costs meaningfully more than manual and earns it back on any product with a legal minimum.

Ask for the thickness tolerance in plus or minus percentage terms. Not every supplier will answer. The ones who answer confidently are usually the ones worth buying from.

Bag making machines

Film is not a bag. The second machine cuts and seals it, and the type must match what you intend to sell.

A bottom seal machine makes the ordinary flat bag with a seal across the base, which covers bread bags, refuse sacks and most general packaging. A side seal machine seals along both sides and gives a cleaner finish for boutique and retail work. A T-shirt or vest bag machine punches the handle and gusset in the same pass, and if shopping bags for supermarkets and markets are your market, this is the machine you need rather than something adapted.

Ask for the speed in cuts or pieces per minute at your actual bag length, not at the shortest length the machine can do. The headline speed is almost always quoted at the length that flatters it.

Printing

Flexographic printing is the standard, and the specification that matters is the number of colours. One or two colours covers most Nigerian branded work, a shop name and a logo. Four gets you into serious retail packaging.

The question to press is registration, meaning how accurately the colours land on top of each other at production speed. Poor registration produces work your customer will reject, and you will only discover it on your first branded order.

Decide too whether printing sits in line with the bag machine or stands alone. Standalone is more flexible and lets you print film for one customer while making plain bags for another. In line is faster if your volume justifies it.

Recycling and the rest of the plant

A crusher and pelletiser turn your trimmings, rejects and start-up waste back into usable material. In a plastics factory that scrap is continuous, so this equipment usually pays for itself faster than anything else you buy. How much regrind you can blend back into the film depends on the product, and pushing it too far shows up as poor film quality before it shows up in your accounts.

Two items get left out of quotations and then hold up commissioning. A water chiller, because the cooling ring needs it and Nigerian ambient temperatures are not what these machines were tuned for. And an air compressor, sized properly rather than borrowed from elsewhere in the plant.

Power, which is the Nigerian question

Ask for the total connected load of every machine in kilowatts, in writing, before you commit to anything.

That figure drives your generator, and generator capacity drives your running cost more than any other decision in the factory. Size the generator on the connected load with real headroom, because an extruder starting against a generator already near its limit is how motors and control boards are destroyed.

An extruder also does not tolerate unstable voltage. A stabiliser and proper protection cost a fraction of a replacement drive, and the machines that arrive in Nigeria are rarely specified with our supply in mind unless somebody asks.

Starting small, and starting right

A workable first factory is one film blowing line, one bag making machine matched to your chosen product, a crusher, a chiller, a compressor and a generator sized to all of it. Printing can wait until you have customers asking for it.

What should not wait is the film line itself. Every other machine on this list can be added, upgraded or replaced without disturbing the rest. The extruder cannot. Buy the one that holds its gauge, and buy the width you will want in three years rather than the width you need in month one.

Before you pay anyone

Most of this equipment comes from China, and the gap between a good line and a poor one is not visible in the photographs, which are frequently the same photographs.

Get the specification in writing: screw diameter, L/D ratio, output by resin type, lay-flat width, thickness range and tolerance, connected load in kW, and what is actually included. Ask what is not in the price, because the chiller, the compressor and the spare die are often outside it. Ask who commissions the line in Nigeria and what happens when a heater band fails in month seven.

Then compare that specification against the price, rather than comparing prices against each other.

The next article looks at raw materials, production costs and profit potential in plastic bag manufacturing, which is where the machine you chose starts showing up in your margins.