Haihui Eastern editorial team · Published 2026-10-21 · Reviewed 2026-10-21
Start with the forming method, not the retail appearance
Injection molding starts with melted plastic introduced into a mold, then cooled and ejected. Thermoforming starts with sheet that is heated and shaped against tooling, followed by separation or trimming. Greiner Packaging describes both methods for packaging; ILLIG identifies vacuum, pressure or combined forming and several forming/punching arrangements.
These are process descriptions, not universal quality grades. A cup, tub or lid may have a similar external appearance when made by different routes. Ask the supplier to identify the process for the proposed body and closure separately. A resin-family name such as PP does not answer that question.
Compare six parts of the proposed pack
Put both offers against the same required function. The following is an original purchasing framework, not a performance ranking or a statement that Haihui Eastern supplies both process families.
Scroll across to compare all columns.
| Review point | Injection-molded proposal | Thermoformed proposal |
|---|---|---|
| Process and material identity | Request the forming route and proposed material for the body and each lid or other component. | Request the sheet construction and forming route for the identified component. Record the actual proposal rather than assuming a route from its appearance. |
| Opening and closure | Identify the opening, lid engagement, seal surface and relevant drawing revisions. | Identify the formed opening and any trimmed or finished edge. Compare the actual lid/seal interface and filling operation, not the nominal capacity alone. |
| Dimensions and wall construction | Ask which dimensions and section details are controlled and how they will be checked on samples. | Ask the same questions for the formed and finished part. Do not substitute a starting-sheet thickness for every finished-wall dimension. |
| Decoration | Confirm the exact IML, printing, label or other route proposed for this model and its lid. | Confirm the actual decoration route, including any thermoforming-specific IML proposal. Appearance does not establish process compatibility. |
| Tooling and quote scope | Identify body and closure tools, design responsibility, sample stage and what the quote includes. | Identify forming, separation/finishing and closure scope where applicable. Compare complete quoted supply rather than a generic tooling-price rule. |
| Sample and change control | Request an identified production-representative assembly and agree checks against the use brief. | Apply the same functional brief. A new forming method, component or construction can reopen prior fit, decoration and intended-use reviews. |
Treat the rim, seal and removable lid as interfaces
Start with the operation the pack must pass through: filling access, sealing, lidding, opening and any required reclosure. Identify which component provides each function. A removable lid and an inner seal are separate items in the comparison, even when the quotation describes them as one closure.
Request the complete opening and outside-envelope drawings, matched component references and the dimensions your filling or sealing equipment needs. Review representative assemblies. Do not transfer approval of an existing lid to a new body because both carry the same capacity description.
An IML label does not prove injection molding
Injection IML is one route to in-mold decoration, but it is not the only forming context. Greiner Packaging’s February 2022 T-IML case explicitly describes inserting a label into a thermoforming mold. ILLIG also lists IML-T decoration units alongside its thermoforming systems. These examples establish that a thermoformed IML route exists; they do not identify the process for an unrelated photographed tub.
For a quoted container, ask for a model-specific process description, decorated surfaces, label construction and artwork approval scope. Confirm the body and lid independently. Supplier examples and industry demonstrations are references, not Haihui Eastern equipment, available models or performance guarantees.
Example: two tubs with the same nominal size
Imagine two proposals using the same capacity description. One identifies an injection-molded body and a matched lid; the other identifies a thermoformed body but leaves the seal and lid references open. This is an illustrative purchasing scenario, not a pair of supplied SKUs or measured samples.
Do not compare the headline unit prices as though the supplies are identical. Align working fill, opening, complete closure, decoration, order quantity, packing and destination first. Then ask each supplier to resolve the missing component and sample scope. The better proposal is the one that can be assessed against the agreed job, not simply the one with a preferred process label.
Compare costs and evidence at model level
Tooling, material use, output and commercial terms depend on the proposed construction and supply scope. Ask for the applicable quotation and sample plan rather than assuming that either method always wins on cost, weight, strength, MOQ or lead time. A supplier’s result for one design is not a transferable percentage for another pack.
Food-contact suitability, transport performance and recycling claims also need their own evidence for the proposed assembly and intended conditions. Changing the forming method does not automatically establish compliance, durability or environmental benefit. Keep these decisions visible in the project review.
Send the constraints before selecting a process
Send the contents, working fill, opening and equipment limits, required closure functions, decoration, quantity per design and destination. Include an existing drawing or sample reference when available. Mark the forming process as a fixed requirement only if it really is one; otherwise explain the functional constraints for review.
Use the Custom Plastic Containers page for a custom container project review. This comparison does not add thermoformed products, equipment or verified supply models to the Haihui Eastern catalog. Proposed availability, materials, dimensions, order terms and approval requirements remain subject to the written project proposal.
Purchasing questions
Can a product photograph show whether a tub is injection molded or thermoformed?
A photograph can show geometry and visible features, but it does not reliably establish the forming method for the exact model. Request a model-specific process statement and drawing, and connect any process footage to the proposed pack.
Does IML always mean injection molding?
No. Injection IML and thermoforming IML routes exist. Confirm the actual forming and decoration process for the quoted body and lid; a named supplier example does not prove the process for another photograph.
Can the same lid and approval be used after changing the body forming method?
Do not assume that they transfer. Review the actual rim, seal and lid references, critical dimensions, use conditions and representative assembly. Record which documents and sample checks remain applicable after the proposed change.
Sources and further reading
- Greiner Packaging — Packaging technologies: injection molding and thermoforming
- ILLIG — Thermoforming systems and forming/punching arrangements
- Greiner Packaging — Named T-IML case, February 15, 2022
General purchasing guidance does not replace the approved model drawing, test results or order terms.