In a lone PU factory, at least four processes touch each other: raw material storage, mixing and dosing, moulding, curing, demoulding, finishing, and packaging. The basic idea in correct layout design is that you want them agreeably and sensibly moved to one another, and not enable bottlenecks and needlessly complicate operations.

Instead of thinking about stand-alone machines, think in terms of a complete polyurethane manufacturing system.

Start from Production Process Mapping

Jot down very clearly what your production process is composed of before starting the picking up pencil.

For a typical PU safety shoe production line or PU rain boot production line, you might have roughly these stages:

• Raw material storage (polyol, isocyanate, additives)
• Metering and mixing (PU dosing machine)
• Injection or pouring (rotary or inline moulding system)
• Curing and cooling
• Demoulding
• Trimming and finishing
• Inspection and packaging

This information will help you avoid the pitfall of placing machines anywhere you can find a space on the shop floor. As a rule, you should get into the habit of ensuring materials move forward through each stage without unnecessary backtracking.

Split Your Factory Into Zones According to Function

Since PU manufacture is a continuous process, you must divide your factory for convenience of operation into different zones for different operations.

Raw Material Store

This may consist of bulk storage tanks, or drums and the feeders. For applications requiring the likes of a BASF Haptex feeder, or if using a water-borne PU, other areas have to be planned for temperature and moisture protection, etc.

This zone must be:

• Close to the mixing/dosing system
• Well ventilated
• Provided with spill protection

Production Zone

This forms the bulk of your factory and where your double density PU shoe machine, rotary moulding arrangement, etc. will be housed.

Check for:

• Sufficient operating area around rotary table
• Logical positioning of mould storage racks, etc.
• Convenient hose and pipeline routing

Finally. Don’t try to cram too many machines in; an over-crowded production zone will create lack of efficiency and high reject rates.

Curing and Cooling Zone

PU injected into its mould must be allowed to cure in still air, etc. Some compact inline conveyors may serve here (or static racks may be used instead).

The air flow, temperature, etc., must be maintained, and there is to be no crosstraffic with the raw materials traffic.

Finishing Zone

The finishing zone will provide for trimming, polishing, bonding, inspection, etc. This zone is all too often not given enough weighing within factory layout system; an ill-furnished zone here can only result in a bottleneck.

Plan for a well-lit area with ergonomic workbenches that is sensibly debarred from dirty process zones.

Packing and Warehouse

Finished goods may do well to go straight to their packing and storing point without passing through the main zone again.

Plan for easy loading and unloading, organized storage and future extension.

Aim the Whole Layout at Articulating Uninterrupted Material Movement

The golden rule is not to think machines only, but how materials move from machine to machine.

Key concepts to keep in mind are:

• Linear or U-shaped flow avoiding backtracking
• Separate routes for incoming and outgoing logistics
• Minimize manual handling wherever possible

Larger facilities may benefit from using conveyors and robotic transfer systems to maintain smoother production at a lower dependency on labor.

Plan for Utilities and Infrastructure Early

PU production uses a lot of equipment; it also needs stable utilities and overlooking this at the layout stage may result in having to hardwire expensive fixups later.

Important utilities include:

• Electrical service (especially where heavy load machinery is used)
• Compressed air
• Temperature control for PU chemicals
• Ventilation and exhaust systems

Piping for polyol, isocyanate and other materials should be as short as convenient and easily accessible.

Leave Space for Maintenance and Future Expansion

Much of a factory’s problems results not from equipment used but because there’s no space available to maintain it.

In designing your layout:

• Leave access space around key machines
• Plan for future production lines
• Constrain arrangements against being too tight

If expansion is a possibility it should be measured into the first layout.

Worker Efficiency and Safety

Good layout makes work easier and safer.

Pay attention to:

• Logical location of workstations
• Reduced movement by the operator
• Clear safety exit paths
• Adequate chemical fume evacuation

For factories coating goods for export all of the above are essential for compliance and audit requirements.

Use Automation Only Where It Matters

Automation doesn’t mean fully automatic systems everywhere, but where it can improve stability of your process, and also help reduce the cost of direct labour.

Examples include:

• Automatic dosing systems
• Rotary moulding machines
• Curing machines based in conveyors

However, in many cases, partial automation can provide stability of output that is good enough for most of the projects.

Work with an Experienced Turnkey Supplier

Trying to design a layout without coordinating with the machines and utilities can lead to mismatch.

When working with a team experienced in supplying PU equipment on a turnkey basis, this will help with:

• Layout of the factory
• Choosing the best equipment to fulfil the requirements
• Installation and commissioning
• Training workers to use the installed machinery

As a result, less trial and error is required and the costs of starting up and stabilising output are reduced.

FAQ

How do you Design a PU Shoe Factory Layout?

You start by mapping the full production process, then dividing the entire factory into functional zones, and ensuring that there is a smooth flow of materials, with proper planning of utilities and space for the final product to be stored and distributed.

What good layout looks like?

While there’s no one-size-fits-all “perfect” layout for a PU shoe factory, the most efficient factories possess some common good properties, like having a linear flow of operation above the floor level and perhaps a U-shape that ensures continuous movement of materials from raw input to finished goods.

How much space do you need for a PU shoe production line?

This depends on the type of machines and capacity you require, but a good working PU safety shoe rotary production line in a standard commercial dimension needs about 800 to 2000 square metre in size excluding the storage and auxiliary space.

How does a bad PU factory layout look like?

• Poor design for the flow of materials around the production operation
• Inadequate maintenance space
• Failure to earmark workshops with adequate supplies and utilities
• Overcrowded production sections

All these bedevil production, and increase cost per product.

Can you retrofit my old plant?

Certainly. Many manufacturers contoured existing PU machines and redesign layout for more efficient flow of materials to each machine instead of building a new factory.

Why is the layout crucial in a PU turnkey project?

Because the layout design affects the entire flow operation, and hence have big implications for production efficiency, final product quality, ease and speed of scaling the plant upwards as capable, and above all, production cost. It actually puts the feet of the giant in PU.