Composites: cure cycles and ovens run with wide margins
Why composite curing and carbon-fibre ovens use conservative cycles and long residence times, and how to check a computed cure state from process data.
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Cure cycles are conservative and long
What happens. A composite part cures in an oven or autoclave on a fixed temperature programme with long holds. The programme is made safe for the thickest part and the coldest spot. Nobody knows how far the resin in the part has actually cured.
What it costs. Oven and autoclave time that limits output, energy for holds that were not needed, and parts that are still sometimes under-cured at an unlucky spot.
Why the usual fix fails. Shortening the programme risks an under-cure that shows up later as a weak part. Thermocouples in a few parts show a few points. Qualification of a new programme takes months, so nobody touches the old one.
How a fixed-price remote diagnosis checks it. From temperature records of the oven and parts, the resin’s cure data and results of past parts I look at how the cure develops across a part. The fixed-price remote diagnosis tells you whether a cure state computed from the temperatures can shorten the cycle safely.
Background: Computed measurements
Oxidation ovens for carbon fibre have long residence times
What happens. In making carbon fibre, precursor fibre passes through oxidation ovens for a long time at carefully set temperatures. The reaction gives off heat, and the fibre state depends on temperature, time and airflow. The line speed is set for safety.
What it costs. Energy for a long residence, a line speed that limits capacity, and fibre quality that varies along the oven.
Why the usual fix fails. Running faster can lead to over-heating and fibre damage. Measuring the fibre state inside the oven is hard. Adjusting zone temperatures by hand depends on lab results that come late.
How a fixed-price remote diagnosis checks it. From oven temperatures, airflow, line speed and the lab results of the fibre I look at how well the fibre state can be computed along the oven. The fixed-price remote diagnosis tells you whether a computed fibre state allows a higher speed or lower energy at the same quality.
Background: Industrial process predictive control
Check it on your plant first: a fixed-price remote diagnosis
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Within a fixed scope and at a fixed price, I review your data, control structure and measurements remotely and tell you whether the problem on this page is behind your symptoms and what fixing it would take. You get a short summary for decision-makers and a technical report for your engineers.