Capacity and lead time

Why the nominal figure misleads

Machine datasheets give an hourly output in linear metres. That is for laboratory conditions and continuous production.

In reality the line does not run continuously:

• coils have to be changed,
• profiles have to be changed over,
• produced material has to be removed and bundled,
• the program has to be loaded and checked,
• there is maintenance and tool changing.

Real capacity is therefore usually a fraction of the nominal figure — and that is not a fault but normal operation.

What sets the real lead time

Material supply

Whether there is enough coil, in the right grade and coating. Procurement is often a longer lead time than production itself.

The number of profile changeovers

Many cross-sections mean many changeovers. So we organise the production sequence by profile rather than by panel — provided bundling can take it.

Assembly

In panelised production the capacity of the assembly table is often narrower than that of profile production.

Logistics

Storage, loading, availability of vehicles. On a tight site this is the strongest constraint.

Readiness on site

Fast production does not help if there is nowhere to put the panels on site, or the foundation is not ready.

How to plan with it

1. Start from the site sequence: what is needed when.
2. Match the production sequence to it, allowing for profile changeovers.
3. Leave a buffer for procurement and for replacing defective members.
4. The first project is slower — trial production and setup take time. Trial production.

The technology’s real time advantage

It is not in production speed but in the fact that site time is short and less weather-dependent: the structure goes up dry, from members made in advance. And foundation work can run in parallel with production.

The point

The speed of the machine is rarely the bottleneck. In scheduling, look at the whole chain: material, production, assembly, transport, site.