Custom Seat Shells Thermoforming Solution for Hvac Equipment in recycled HDPE

Vacuum formed seat shells are used across HVAC equipment because they can be produced without the tooling spend of injection moulding and without the weight of sheet metal. This page covers how 2 mm recycled HDPE sheet is formed for HVAC equipment, what tolerances are realistic, and what has to be on the drawing before tooling starts.

The route below is the one used for most of the seat shells shipped from this plant: sheet is heated on the forming machine, drawn over an aluminium or composite mould, cooled on a jig, then trimmed on a 5-axis router. For seat shells the sheet gauge is selected from the load case rather than from habit, and recycled HDPE is the material most often specified for this combination.

Typical specification

Where these parts are used

• unit covers for HVAC equipment
• fan shrouds for HVAC equipment
• condensate trays for HVAC equipment
• duct end caps for HVAC equipment
• seat shells in general HVAC equipment builds

How the part is made

1. Drawings are reviewed and a manufacturability report is issued with wall thickness, draft and radii marked up.
2. Tooling is cut: aluminium for production volumes, composite or printed moulds for samples and first articles.
3. Sheet is dried when the material needs it, then heated to forming temperature on the machine.
4. The sheet is formed over the mould with vacuum and, where the draw is deep, with plug assist.
5. The part cools on a jig so the shape is held while the material stabilises.
6. Trimming is done on 5-axis routers or with a dedicated trim fixture to meet the drawing.
7. Parts are inspected, fitted with inserts or hardware if required, packed and shipped.

Material notes: recycled HDPE

Recycled HDPE sheet lowers material cost and supports sustainability targets, with mechanical properties close to virgin sheet for non critical parts.

Design tips for this part

• avoid sharp steps in the mould, which show as chill marks on the finished surface
• keep a draft angle of at least 3 degrees on vertical walls so the part releases cleanly
• call out the finish on the drawing: mould texture, paint, or as-formed gloss
• hold the draw ratio near 1:1 for deep parts, or specify plug assist
• use corner radii of at least three times the sheet thickness to avoid thinning

Quality and inspection

Batch releases carry a dimensional report, material certificate and, where agreed, PPAP or ISIR documentation. Moulds, trim fixtures and programmes are stored against the part number, so a repeat order matches the first batch.

Cost and lead time

Tooling is the main cost driver at low volume, so a 2 mm seat shells for HVAC equipment is usually quoted with a composite or printed mould first and the aluminium tool cut once the design is frozen. That keeps the first article cost low and gives a real part to test before the production tool exists. The result is lower tooling cost compared with the alternatives, and a piece price that stays stable across repeat releases.

• Sample tooling: 7–15 working days
• Production tooling: 3–4 weeks
• Repeat orders run on stored tooling with no new proving run

Frequently asked questions

Do you supply certificates?

Material certificates, dimensional reports and flame retardancy or food contact declarations are issued with the shipment where the specification requires them.

What quantities make sense?

Vacuum forming pays off from roughly 25 pieces up to several thousand a year. Below that, printed or composite tooling keeps the setup cost low.

How long does tooling take?

Sample and first article tooling is usually cut in 7 to 15 working days. Production aluminium tools take 3 to 4 weeks depending on size and cooling layout.

Getting started

Send the drawing or a photo of the current seat shells with the quantity and the finish. The first reply is a manufacturability review with the wall thickness, material and a quotation, so the decision is made on facts rather than on a price alone.