Thick sheet forming, also known as heavy-gauge thermoforming, is transforming how companies create durable packaging and components today. Analysts estimate thermoform packaging at approximately USD 49 billion in 2024 with steady growth through 2034, reflecting strong demand in food, medical, and industrial applications.

In this comprehensive guide, we’ll explore what thick sheet forming entails, why it matters in 2025, and how to leverage it effectively. From process basics and key benefits to common mistakes to avoid and a quick-start checklist, you’ll learn how thick sheet forming can deliver strong, sustainable packaging solutions. By the end, you’ll see why innovative providers like Superpak (a one-stop packaging partner with 30+ years of experience) are trusted to turn thick sheet forming into a competitive advantage for your business.

What is Thick Sheet Forming?

Thick sheet forming is a manufacturing process where a thick thermoplastic sheet (often several millimetres thick) is heated until pliable and then formed over a mould using vacuum or pressure, creating a rigid three-dimensional part. It’s essentially the heavy-duty side of thermoforming, working with much sturdier plastic sheets than the thin films used for typical blister packs or clamshells. After forming, the part cools and retains the mould’s shape, then any excess is trimmed off. The result is a strong, precise plastic component or package.

In industry terms, thick sheet forming (heavy-gauge thermoforming) usually refers to sheets around 2 to 10 mm thick, versus “thin-gauge” forming for sheets under 2 mm. This thick-gauge approach produces robust items like equipment housings, reusable trays, machine guards, automotive panels, and other structural or packaging components that need greater strength. For example, an electronics manufacturer might use thick sheet forming to create a custom tray that safely holds delicate circuit boards, or a medical supplier might thermoform a sturdy instrument case.

To form these thick sheets, manufacturers employ specialised thermoforming machines with high heating power and strong vacuum pumps or pressure systems. In vacuum forming, the hot sheet is draped over a mould, and vacuum suction pulls it into the mould’s shape. In pressure forming, additional air pressure (and sometimes a plug assist) is applied to the sheet, pressing it firmly into the mould for crisper details. Pressure forming is often paired with thick sheet materials to achieve finer features and tight tolerances approaching injection moulding quality. In some cases, twin-sheet forming is used, where two heated sheets are formed and fused, creating hollow, double-walled parts with exceptional rigidity (like air pallets or fuel tanks).

Overall, thick sheet forming allows the creation of large, durable plastic parts with relatively low tooling cost and design flexibility. As we’ll see, this makes it an attractive solution for many packaging challenges.

Why Thick Sheet Forming Matters Today

In 2025, thick sheet forming is getting plenty of attention across industries. A big part of that story is simple market demand. The global thermoformed plastics and packaging sector is on the rise, with food packaging taking the lead. In fact, food and beverage applications made up more than 42% of sales in 2023 and grew to 52% in 2024,  and the share is expected to keep climbing well into the 2030s.

But growth isn’t just about volume. Another key factor driving adoption is the push for sustainability and efficiency. Thick sheet-formed packaging can often replace traditional wood, metal, or cardboard solutions with lighter-weight, recyclable plastics. For example, heavy-gauge thermoformed packaging used for electric vehicle components is designed to be 100% recyclable, and many firms are embracing returnable, reusable plastic trays and pallets to minimise waste.

Industry trends also favour thick sheet forming. Sectors like automotive and electronics are increasingly using heavy-gauge thermoformed parts as lightweight alternatives to metal, delivering weight savings without sacrificing performance. Additionally, advances in thermoforming technology, like better temperature controls, CNC trimming, and simulation, make it easier to form thick sheets with precision. As labour costs rise and timelines shorten, the relatively quick tooling and prototyping of thermoforming (versus, say, injection moulding) is appealing for getting products to market faster.

Finally, safety and compliance requirements highlight the value of thick sheet-formed packaging. In medical and semiconductor fields, there’s demand for cleanroom-safe, ESD-safe trays and enclosures, materials, and processes have to align with standards like ANSI/ESD S20.20 for ESD control and cleanroom-compatible production. Companies like Superpak, which is ISO 9001:2015 and ISO 14001:2015 certified, are leveraging thick sheet forming to deliver packaging that meets strict standards while also supporting sustainability.

In short, thick sheet forming sits at the intersection of durability, innovation, and sustainability, which is exactly why it matters more than ever today.

How Thick Sheet Forming Works (Process Overview)

1. Heating the Sheet

A plastic sheet (e.g. ABS, polycarbonate, HDPE, etc.) is clamped in a frame and heated in an oven. Thick sheets need high heat and sometimes more time to become uniformly pliable due to their mass. Modern machines use precise temperature controls to avoid overheating or warping the sheet.

2. Forming Over the Mould

Once soft, the sheet is immediately moved over a mould. For vacuum forming, the mould usually has tiny holes, and a vacuum pump sucks air out from under the sheet, pulling the hot plastic down onto the mould surface. For pressure forming, vacuum is combined with compressed air pushing from above (and/or a mechanical plug assist) to force the sheet into detailed mould features. Pressure forming is especially useful in thick sheet forming to capture sharp corners, textured surfaces, and fine details that vacuum alone might miss.

3. Cooling and Release

The formed plastic cools for a short time. As it cools, it hardens into the shape of the mould and is then removed. With thicker parts, cooling is critical to avoid residual stress and maintain shape/strength.

4. Trimming and Finishing

Any excess plastic is trimmed off, often with 5-axis CNC routers for precision, then holes or features are added, edges finished, and secondary operations (e.g., labelling, barcoding, assembling subcomponents) performed as required.

Throughout this process, maintaining uniform material thickness is a challenge, especially with deep or complex moulds. Mould design, plug assists, and proper draft angles help ensure even distribution and demoulding.

Materials: Thick sheet forming works with a variety of thermoplastics. Common choices include ABS (impact resistance), polycarbonate (toughness and heat), HDPE (tough and chemical-resistant), HIPS (rigid and cost-effective), PETG (clear and sterilisable for medical use), and others. PETG grades used for medical trays are compatible with common sterilisation methods (EtO, gamma, e-beam).

It’s worth noting that thick sheet thermoforming generally suits larger items or moderate production runs. For example, injection moulding may be more efficient for very high volumes of small parts, but carries much higher tooling costs and lead times.

Benefits of Thick Sheet Forming for Packaging

Durability and Strength

Thick-gauge thermoformed parts are tough and can endure rough handling and repeated use, making them suitable for reusable packaging such as returnable trays and bins.

Large Part Capability

Thick sheet forming readily handles large dimensions and deep draws. For reference, Superpak lists a maximum forming area of W600 × L1200 × H400 mm for its thermoforming equipment.

Lower Tooling Costs & Faster Setup

Thermoform moulds are significantly less expensive and faster to build than comparable injection moulds. These are ideal for small-to-midsize runs and faster iteration.

Design Flexibility

Heavy-gauge thermoforming enables intricate shapes and crisp details, especially with pressure forming, supporting moulded-in textures, logos, and sharp styling lines.

Lightweight & Efficient

Thermoformed plastic parts can substantially reduce weight versus metal while maintaining needed performance, cutting shipping costs and easing handling.

Cost Savings Over Time

Durable thermoformed packaging can replace disposable materials and lower long-term costs, as it can be reused many times. This significantly reduces ongoing material expenses and disposal fees associated with single-use items.

Cleanliness and Safety

Thick plastic packaging can be washed/sterilised and formulated for ESD or flame-retardant needs; PETG medical trays are widely used due to sterilisation compatibility. For ESD control requirements, refer to ANSI/ESD S20.20 and related controls.

Sustainability Options

At the end of a product’s life, these materials can often be fully recycled, allowing them to be reprocessed and used again. Many programs now use recycled content or design for reuse and end-of-life recycling. In a single process, manufacturers can use recycled content to produce durable packaging that is also engineered for reuse in returnable systems, like the trays for EV components.  

Common Applications and Industries

Reusable Shipping Trays & Dunnage (automotive, electronics)

Returnable, stackable heavy-gauge thermoformed trays protect parts in transit and assembly.

Equipment Housings & Enclosures

Pressure-formed housings (medical, industrial) achieve cosmetic surfaces with moulded-in details.

Pallets, Totes, and Bins

Twin-sheet thermoforming produces hollow, double-walled parts with excellent rigidity for pallets and containers.

Consumer Product Cases

Durable clamshell cases and protective shells suit moderate volumes and custom inserts.

Aerospace and Defence Components

Large, contoured panels and covers benefit from lightweight and design flexibility.

Medical & Pharma Trays

PETG trays for sterile barriers and instrument kits are common due to clarity and sterilisation compatibility.

Semiconductor/Cleanroom Packaging

ESD-safe trays and carriers support sensitive devices within controlled environments.

→ Learn more with Custom Thermoformed Trays in Singapore: Precision Packaging for Electronics & Medical Devices. This article explores how thick sheet-formed trays are tailored for the electronics and medical industries, highlighting real-world examples of improved protection and efficiency.

How to Implement a Thick Sheet Forming Project (Step-by-Step)

1. Define Requirements and Goals

Clarify exactly what the part must do and under what conditions it must perform. Capture:

• Environment: temperature range (cold chain, outdoor heat), humidity, UV exposure, chemicals/cleaners, sterilisation method (if any).
• Performance: impact/drop resistance, load-bearing points, stiffness, surface cosmetics, noise/vibration.
• Compliance: food contact, medical sterility, ESD control, flame retardancy, RoHS/REACH where relevant.
• Commercials: annual/batch volumes, target unit cost, tooling budget, launch date, sustainability targets (recycled content, recyclability).
• Logistics: dimensional envelope, nesting/stacking constraints, pallet fit, line-side handling and automation needs.
  
  

2. Consult with an Expert Partner Early

Design-for-manufacture (DFM) collaboration at the concept stage saves time and rework. Share a brief, CAD (even rough), expected volumes, and quality requirements. In a short DFM workshop, your thermoforming partner will:

• Confirm draw direction, parting lines and feasible draw ratio; flag deep draws that need plug-assist.
• Advise minimum draft, radii, rib patterns and trim allowances; suggest material gauge and texture options.
• Outline tooling route (prototype → production), indicative timings, and risks with mitigations.
• Align on measurement datums, inspection plan and acceptance criteria for first-article approval.
  
  

3. Choose the Right Material

Match performance, compliance and aesthetics before you lock geometry. Typical heavy-gauge options:

• ABS: tough, easily formed, good cosmetics; common for housings and trays.
• Polycarbonate (PC): very high impact/heat resistance; good for guards and demanding environments.
• HIPS/PS: rigid and economical, where high impact is not critical.
• HDPE/PP: chemical resistance and toughness for industrial trays and dunnage.
• PETG: clear, formable and compatible with common sterilisation methods for medical trays. Options include UV-stabilised, ESD-dissipative, or flame-retardant grades, and recycled-content sheet where specification allows. Select sheet gauge based on draw depth and desired wall thickness after forming. Confirm food/medical approvals and regional recycling pathways where applicable.
  
  

4. Design the Part (with Thermoforming in Mind)

Apply thermoforming-friendly rules so parts release cleanly and hold tolerance:

• Draft angles: generally start at around 3°. Increase for textured surfaces, deep draws or male tools.
• Radii & transitions: use generous inside radii (often ≥ sheet thickness; larger on deep draws) to reduce thinning and stress.
• Wall-thickness strategy: avoid large, solid masses. Use ribs/gussets for stiffness.
• Undercuts & features: minimise undercuts; if unavoidable, plan split tooling or post-forming operations.
• Trim & datums: include a trim allowance and mould-in datum faces/targets to stabilise 5-axis trimming.
• Functionality: integrate stacking features, label recesses, drainage, locating pins or handle scallops early, not as add-ons.
  
  

5. Build the Mould and Prototype Parts

De-risk with a prototype tool to validate function and cosmetics before investing in production tooling. Typical approach:

• Tooling: soft aluminium, epoxy, or high-density model board; add plug-assist for deep cavities.
• Sampling: run enough parts to test assembly fit, nesting, line handling and packaging.
• Validation: measure critical dimensions (CMM/scan), perform thickness mapping, basic drop/impact or thermal conditioning, and any sterilisation/cleaning trials as relevant.
• Feedback loop: capture user/operator feedback and log any NCs for design updates.
  
  

6. Iterate and Finalise Production Tooling

Incorporate learnings, then commit to durable aluminium tooling with proper process control:

• Temperature control: cooling/heating channels and zoned heaters for repeatability.
• Venting: correct vacuum port sizing and placement for sharp detail without witness marks.
• Surface finish: texture or bead-blast as specified; confirm gloss levels against brand standards.
• Trim tooling: design fixtures and 5-axis paths; provide hard datums and clamping points.
• Change management: consider interchangeable inserts for variants and future-proofing.
  
  

7. Production and Quality Control

Lock the process and prove capability before full release:

• Process windows: document heat profiles by zone, target sheet temperature, vacuum/pressure set-points, and cycle times.
• First-Article Inspection: agree on CTQs, tolerances and sampling plans; retain golden samples.
• In-process controls: SPC on key dimensions, thickness checks at high-strain regions, visual standards for cosmetics.
• Traceability: lot control on sheet stock; traveller/route cards; revision control on programs and trim paths.
• Standards: align to your supplier’s quality system (e.g., ISO 9001) and environmental controls (e.g., ISO 14001) for documentation and audits.
  
  

8. Delivery and Integration

Plan the downstream flow so parts arrive, work first time, and, if returnable, keep circulating:

• Protection & packing: specify protective films, dividers or interleaf to avoid scuffing; design nesting/stacking to maximise cubic efficiency.
• Line integration: provide orientation markers, barcodes/QRs, and handling SOPs for operators or robots.
• Reverse logistics: for returnable trays, set rules for cleaning, inspection, repair and end-of-life recycling.
• Spares & maintenance: stock trim fixtures and wear parts; schedule preventive maintenance on tools and routers; document a fast-response path for engineering changes.
  
  

Common Mistakes in Thick Sheet Forming And How to Avoid Them

Even with advanced machinery, the success of a thick sheet thermoforming project depends heavily on smart design choices. Many issues arise not from the process itself, but from avoidable design oversights. Here are the most common mistakes and why they matter.

Not Designing with Draft Angles

A part without sufficient draft angles (the slight taper on vertical walls) can easily stick to the mould or become damaged during release. Industry guidelines recommend around 3 to 5 degrees of draft, with even more required for textured surfaces or male moulds. Ignoring this detail can lead to production delays, tool damage, and higher scrap rates, all of which add unnecessary cost.

Uneven or Overly Thick Sections

Thermoformed parts perform best when the wall thickness is uniform. Designers sometimes “mound up” material in certain areas for strength, but this often creates sink marks, warping, or cooling issues. Instead, use ribs and gussets to reinforce the part without adding unnecessary bulk. This not only improves performance but also reduces raw material usage, directly lowering costs.

Overly Sharp Corners and Small Radii

Sharp corners may look clean on CAD, but they rarely work in thermoforming. They concentrate stress, cause thinning during forming, and make it harder for the sheet to flow into the mould. Generous radii improve strength, reduce the risk of webbing, and extend the life of the part. A rule of thumb: larger radii lead to more consistent wall thickness and stronger components.

Choosing the Wrong Material

Not all plastics perform the same way. A material suitable for indoor housing might fail outdoors when exposed to UV, chemicals, or temperature extremes. Matching the resin to the application environment is crucial. For example, PETG offers clarity and sterilisation compatibility for medical products, while HDPE excels in impact-resistant returnable packaging. The wrong choice could mean premature failure or costly redesigns.

Skipping Prototyping and Testing

Jumping straight to full-scale production tooling is risky. Without a prototype run, you won’t know whether the part fits, functions, or cools properly. Prototyping allows engineers to validate dimensions, catch defects early, and make cost-effective changes before investing in expensive aluminium tools.

Neglecting Quality Processes

Even the best design can fail without tight process control. Consistent heating, proper forming pressures, and cooling cycle monitoring are essential to reduce variability. Partnering with ISO-certified thermoforming suppliers ensures that every production run meets the same standard, which is especially important in regulated industries like medical devices or automotive.

Engaging Suppliers Too Late

One of the biggest mistakes is treating the thermoforming supplier as an afterthought. Involving them early brings design-for-manufacturability expertise to the table, helping you avoid features that are difficult or impossible to form. Early collaboration saves time, prevents costly tool changes, and speeds up time-to-market.

Frequently Asked Questions (FAQs)

Q: What’s the difference between thick sheet forming and thin sheet thermoforming? 
A: The difference lies mainly in sheet thickness and end use. Thin-gauge (< 1.5 – 2 mm) is typically for disposable packaging, while heavy-gauge (> 3 mm) produces durable structural parts like trays, housings, and panels.

Q: When should I use thick sheet forming instead of injection moulding?
A: Thick sheet forming and injection moulding are both excellent for plastic production, but they serve different needs. Thick sheet forming is ideal for projects that require larger parts, faster turnaround, and lower initial investment. Its tooling costs are a fraction of injection molding, and moulds can be created in weeks instead of months. This makes it a great choice for prototyping, medium-volume runs, and products with simpler geometry.

Injection moulding is the preferred method for projects that demand very high volumes and ultra-fine detail. Although its tooling is far more expensive and time-consuming, the process excels at producing small, intricate parts with tight tolerances. The high production speed and automation of multi-cavity moulds make it the most cost-effective solution for mass production.

Q: What materials can be thermoformed in thick sheets?
A: Many thermoplastics are available in heavy gauges, including ABS, PC, HIPS, HDPE, PETG, and more. These are selected based on performance, appearance, and compliance needs.

Q: Is thick sheet-formed packaging recyclable or eco-friendly?

A: Often yes. Many projects use recyclable materials and returnable systems (e.g., reusable thermoformed trays/pallets), with end-of-life recycling possible. Providers like Superpak also offer specialised services, such as collection and washing programs, to extend the lifespan of returnable packaging and further minimise waste.

Conclusion

Thick sheet forming is a powerful solution for improving your packaging and components and the knowledge you have is the first step. Now, it’s time to put it into action. At Superpak, we pride ourselves on being a collaborative partner who can simplify the entire process, from design brainstorming to production and logistics.

Let’s work together to build it right the first time. Tell us your needs and we’ll propose a practical, made-to-measure plan to help you cut costs, boost sustainability, and delight your stakeholders