Plastic Egg Tray Making Machine: What It Produces, and How It Differs from Molded Pulp

If you are looking for a machine to make molded pulp egg trays — the grey-brown fibrous trays pressed from waste paper — this page is about a different machine, and you should look for a pulp molding line supplier instead.

This page covers plastic thermoformed egg trays: rigid trays formed from PP, PS or PET sheet, the type used for retail egg cartons, branded trays and washable returnable trays.

Both products are sold under the same search term, and the two machines share almost nothing. Getting that distinction right before you request a quotation saves months.

The confusion is understandable. Both products hold eggs, both are called egg trays, and both are produced "automatically". The processes are unrelated.

Molded pulp starts with waste paper and water. The pulp is drawn onto wire mesh molds by vacuum, the wet shape is released onto a conveyor, and the trays are dried in a long oven. The tooling is mesh, the output is fibrous, and the whole line is dominated by the drying stage, which is why pulp lines are long and energy-heavy.

Plastic thermoforming starts with plastic sheet on a roll. The sheet is heated until it softens, formed over or into a metal mold by vacuum and air pressure, then cut from the sheet and stacked. There is no drying stage and no water in the process. The tooling is an aluminium mold, and the output is a rigid plastic tray with a defined wall thickness.

If your requirement is the left column, stop here — that is a genuine and useful product, but it is not what HengXing builds. If it is the right column, the rest of this page is for you.

Four formats cover most of the market, and one machine with interchangeable molds can run all of them:

30 eggs, 5 × 6 grid — The bulk transport tray. No lid. Designed to stack on corner lugs so that loaded trays bear load through the posts rather than through the eggs.

20 eggs, 4 × 5 grid — The bulk tray for smaller runs and for grading lines that pack by weight band rather than by fixed count.

10 eggs, 2 × 5 grid — The retail carton. Hinged lid formed in the same cycle, with side locking tabs and a label area on the lid face.

6 eggs, 2 × 3 grid — The retail carton for premium and specialty packs.

The design details matter more than the outline. A tray that looks right on a drawing but performs badly in a grading line usually has one of these wrong:

• Egg posts between cells — they carry the stack load. Too thin and they fold under a full pallet.
• Cushioning ribs at the base of each cell — they absorb shock in transit and stop shell contact with the tray floor.
• Ventilation slots — needed for rapid cooling after washing and for airflow in cold storage.
• Denest ribs — stop empty trays locking into each other when they come off the stacker.
• Stacking lugs — set the loaded stack height and keep columns vertical on a pallet.
• Hinge and locking tabs on retail cartons — a hinge formed too thin cracks on the first open.

These are mold decisions, not machine decisions, but they are made at the same time as the machine specification. That is why sending only a machine enquiry without the tray drawing tends to produce a quotation you cannot use.

Egg trays are usually one of three materials, and the choice is driven by the sales channel rather than by the machine.

PS (polystyrene) — The lowest-cost option. Opaque, rigid, forms cleanly at thin gauges. It is the standard choice for bulk transport trays where the buyer never sees the tray and price decides the order.

PET — Clear, so the product is visible, which suits retail and branded eggs. It also shows defects: cracks and thin spots become visible under candling, which is either an advantage (quality control) or a problem (rejects), depending on your process control.

PP (polypropylene) — Tougher, and tolerant of washing. The right material for reusable and returnable tray programmes, where the tray has to survive multiple trips and a wash cycle rather than a single journey.

All three run on the same machine with different heating and forming settings. The practical constraint is not the material list but whether the machine's heating zones and recipe storage can hold a stable profile per material — switching between PS and PP without zone control means re-tuning the line by trial and error every time.

Sheet infeed → Heating → Forming → Cutting → Stacking

The sheet is indexed from the roll into the heating section, where it is brought to forming temperature. It then moves to the forming station, where vacuum draws it onto the mold and positive air pressure from above presses it into the cavity detail — the egg posts and cushioning ribs are exactly the kind of fine detail that pressure forming reproduces and vacuum-only forming rounds off.

After forming, the tools close on the sheet and cut the trays free. The finished trays are counted and stacked at the end of the line.

Because egg trays are shallow — a standard 30-egg tray is typically 60–70 mm deep — the forming depth is rarely the constraint. The constraint is how many tray cavities fit in the forming area, because that number multiplies directly into output.

Three figures worth reading carefully.

150 mm forming height against a 60–70 mm tray leaves substantial headroom. That headroom is what lets the same machine run lidded retail cartons and deeper specialty trays without changing platform.

650 × 750 mm forming area is the number that sets your output, because it determines the cavity count.

117 kW rated furnace, 30–50% actual draw is the number that sets your running cost. Egg trays are thin-wall work, so the furnace rarely runs at nameplate — but the installed capacity still has to be there for the first minutes of a cold start.

The arithmetic is simple, and most quotations do not show it:

Trays per hour = cavities per cycle × cycles per minute × 60

An illustration, using a hypothetical 2 × 2 layout — four 30-egg trays per cycle:

• At 15 cycles per minute: 4 × 15 × 60 = 3,600 trays per hour
• At 10 cycles per minute: 4 × 10 × 60 = 2,400 trays per hour

The same machine, the same mold, a 50% difference in output. The variable is cycle time at your actual sheet thickness, not the headline molds-per-minute figure printed in a brochure.

This is also why the cavity layout is worth engineering properly before the mold is cut. Going from four cavities to six raises output by half without touching the machine — but only if the tray footprint allows it and the wall thickness still holds at the corners. That trade-off is decided on the drawing, not on the shop floor.

Egg trays sell at a low unit price, so the only thing that matters economically is cost per thousand trays. Two inputs dominate it:

Material weight per tray. Thin-wall forming saves material on every single tray, multiplied by millions. But you can only reduce wall thickness if the wall is even — uneven walls mean thin corners that crack in the grading line, and the rejects cost more than the material saved.

Downtime between formats. A plant running 30-egg bulk trays in the morning and 10-egg retail cartons in the afternoon loses money on every hour of changeover. Recipe storage and automatic mold locking turn that from hours into minutes.

Comparing machines on purchase price alone hides both of these. Comparing them on cost per thousand trays at your cavity count, your wall thickness and your format mix is the only comparison that holds.

Six things let us answer with a configuration and a cycle time rather than a price range:

1. Tray drawing or a physical sample
2. Egg count and grid layout (30 / 20 / 10 / 6)
3. Material — PS, PET or PP
4. Sheet thickness you intend to run
5. Target output per shift, or per hour
6. Whether you need retail cartons with hinged lids

With those, we can tell you the cavity layout that fits the forming area, the cycle time at your wall thickness, and the auxiliary equipment — chiller, compressor, granulator — sized to match.

HengXing Blister Machinery (Shenzhen) Co., Ltd. Website: https://www.hxblistermachine.com/ Email: hxmachinery@outlook.com WhatsApp: +86 180 3814 9443