The molded pulp manufacturing process runs in eight stages: design, tooling, pulp preparation, forming, hot pressing, trimming, finishing and quality checks. In wet press, the formed fibre goes straight into heated tooling, which sets the shape and gives the part its thin walls and smooth surface. We confirm the design on a product test fit and a physical prototype before production, within our ideal lead time of 3 to 6 weeks.
Key Takeaways
- The molded pulp process involves designing the part around the product and its packaging, developing the tooling, forming the fibre slurry in a mold, hot pressing, trimming, finishing and checking, in that order.
- Design comes first. The product, its accessories and the outer packaging determine the shape, and the part must have a draft and rounded corners for easy release from the mold and even forming.
- A three-piece set of tooling is used: the forming mold with a mesh surface, the hot press mold consisting of two halves, and the trimming die, usually made of aluminium or tool steel.
- Our process is wet press. The preform is formed wet and transferred directly to the hot tooling, and this produces thinner walls, sharper detail and a smoother surface than dry press.
- In hot pressing, the shape, the surface finish and the structural integrity are all fixed at once, because the heat and pressure dry out and compress the fibre against the tool surfaces.
- All features that could be made integral with the mold, such as embossing the logo, must be considered in advance of the tooling design.
- Parts are checked for fit, wall consistency, edges, dimensions and dryness against the product and the prototype you approved, and heavier or fragile products get load and handling checks agreed with you.
- Our lead time is ideally 3 to 6 weeks. A first run needs new tooling, a repeat order reuses it and can move faster, and the minimum order quantity for molded pulp is 30,000 pieces and above.
The molded pulp product appears simple once it has been delivered to you, being nothing but a perfect fit tray holding the item in place. This seemingly simple product actually involved a series of design and production processes, and any error committed along the way would result in an imperfect final product.
This document is aimed at brands and manufacturers in Malaysia who are considering manufacturing of molded pulp items including electronics, cosmetics, pharmaceutical, and food & beverage goods. In this article, we will consider the stages of the molded pulp manufacturing process step by step and in the right sequence to understand why it is important for this process and what the steps include: part designing, tooling manufacturing, pulp preparation and forming, hot pressing, trimming, finishing and quality checking. We have been engaged in manufacturing packaging for more than 40 years, and our successful molded pulp projects are those when the design and tooling have been worked out before the first part forming.
01. What Are the Stages of the Molded Pulp Manufacturing Process?
Molded pulp manufacturing is a process of making a firm product based on fibre and water. This process includes two major steps: what should be decided before production, such as design and tooling, and what goes on the production line, such as pulp preparation, forming, hot pressing, trimming, finishing and controls. Below you can find all 8 stages of this process and what decision making comes under each of them.
| Stage | What happens | What it decides |
|---|---|---|
| Design | The part is shaped around the real product, its accessories and the box it sits in | How well the part fits and holds the product |
| Tooling | Metal molds are machined for forming, hot pressing and trimming | Dimensions, surface finish and how alike every part is |
| Pulp preparation | Fibre is broken down in water into a smooth slurry | How evenly the fibre builds up on the mold |
| Forming | Vacuum draws the slurry onto a mesh mold to make a wet preform | Wall thickness and fibre spread |
| Hot pressing | The wet preform is pressed and dried between heated molds | Final shape, density and surface smoothness |
| Trimming | The edge is cut to the exact outline | Clean edges and exact size |
| Finishing | Details such as embossing are completed and loose fibre is cleaned off | How the part looks and feels in the hand |
| Quality checks | Parts are checked against the product and the approved prototype | Whether the run matches what you signed off |
Each stage depends on the one before it. A thin wall formed at stage four cannot be fixed by pressing at stage five, and a loose fit built into the design cannot be fixed by tooling. That is why we settle the design and confirm the fit first, and why the sections below follow the same order.
02. Why Is It Beneficial to Know About the Process of Molded Pulp Prior to Ordering?
Most of the molded pulp issues are not discovered during the delivery of parts; rather, they appear during the development phase (in the process of designing, creating tooling, and pressing). Understanding the sequence of the process will help ask relevant questions when it is possible to receive an adequate answer.
- Finish and fit are determined during the design phase since they depend on the wall thickness and positioning of the part and cannot be achieved later, thus, these issues must be addressed during the design.
- It is better to address any changes prior to the creation of tooling since any changes in the shape or logo after the tooling creation will require changing or remaking of the tooling; thus, these issues must be addressed first.
- Tooling determines the timeline of production: a first run will require tooling creation which is the most time-consuming step of all, and re-ordering of already existing tooling does not require its creation.
- Tooling and press time are determined for each design; thus, the quantity for each design is estimated together with you in advance.
None of this needs technical knowledge on your side. It needs the right information early: the real product, the box around it, the quantity and any detail that has to be built into the mold.
03. How Does Wet Press Differ From Dry Press Molded Pulp?
Molded pulp is made in two main ways, and the choice changes the thickness, surface and detail of the part. In dry press, the formed pulp is dried first and then pressed. In wet press, the formed pulp goes into heated tooling while it is still wet and is pressed and dried in one step. Wet press is the method we use.
| Factor | Dry press | Wet press |
|---|---|---|
| Surface | Flat front, rougher back, the eggshell look | Smooth, even and finished |
| Wall thickness | Thicker, typically about 1.5 to 3 mm | Thinner, typically about 1 mm |
| Detail | Softer edges and corners | Sharper detail and a tighter fit to the product |
| Drying | The wet blank is dried before it is pressed | Pressed and dried directly in heated tooling |
| Press time | Short, a few seconds a press | Longer, so tooling is made with several cavities |
| Typical use | Appliances and transit packaging that needs thick cushioning | Electronics, cosmetics and presentation packaging |
The thickness figures are typical industry ranges, not our specification. The wall thickness of your part is set at the design stage. What does not change is the reason wet press is chosen for presentation packaging: the heated, polished tooling gives the smooth inner tray finish people expect inside a premium device box, and it asks for more precision in the tooling to get there. The rest of this guide follows the wet press route.
04. How Is a Molded Pulp Part Designed?
Design is where the process is won or lost, because the tooling is cut from it. We start from the specification: the size and weight of the product, every accessory that needs its own space and the box the part will sit in. Then we check the real product against those dimensions in a product test fit before any shape is drawn. Only once the fit is confirmed do we design the part.
Molded pulp has its own design rules, because the part has to come off a mold without tearing and the fibre has to build up evenly. These are the features we settle with you.
| Design feature | Why it matters | What we settle |
|---|---|---|
| Draft angle | Walls need a slight slope so the part releases cleanly from the mold | The slope of every wall and cavity |
| Rounded corners | Sharp corners are harder to form evenly and tend to become weak points | The radius at edges and at the bottom of each cavity |
| Wall thickness | Thickness sets the strength of the part and how snug the fit feels | Thickness across the part, with strength added by shape, not bulk |
| Ribs and raised walls | They take up movement and stiffen the part without adding material | Where each rib sits and how tall it is |
| No undercuts | An overhang would lock the part onto the mold | Cavity shapes that can be released in one movement |
| Cavity depth | Deep, narrow cavities are harder to form evenly | Depth in proportion to the opening, and where a product needs a deeper seat |
We also leave a small, deliberate clearance around the product, so it seats easily and does not bind against the walls. A part that grips too tightly is as much a problem as one that lets the product move.
05. What Is Pulp Mold Tooling?
Pulp mold tooling is the set of metal molds that gives the part its shape. It is built for one design, which is why it is made after the design is confirmed, and why a repeat order on the same design can reuse it. A wet press part needs three tools working as a set.
| Tool | What it does | What it affects |
|---|---|---|
| Forming mold | A mesh covered mold that sits in the slurry while vacuum draws water through the mesh and the fibre collects on its surface | Fibre spread and wall thickness |
| Hot press mold | A matched pair, one convex and one concave, that closes on the wet preform and presses and dries it under heat | Final shape, density and surface smoothness |
| Trimming die | A cutting die that cuts the pressed part to its exact outline | Edge quality and overall dimensions |
Tooling for precise work is typically machined from aluminium or tool steel on CNC machines, and the surfaces that touch the fibre are finished to give the smooth look that wet press is chosen for. The mesh on the forming mold matters as well, because its fineness affects how evenly the fibre lays down and what texture the part carries.
Wet pressing cycles are slower than dry pressing, hence tooling is made up of several cavities; this implies that more parts get formed in the process. The number of cavities depends on the size of the part and the capacity of the press machine, and the number is decided at the design phase. However, molds wear out in time, hence have to be maintained and inspected for quality between the runs to ensure that all parts are formed in accordance to required specifications.
06. How Is the Pulp Prepared?
Pulp preparation is the silent phase that determines how well the molding process goes. The mixture consists of bamboo, bagasse and recycled paper fibre in such a way that it fits the type of product we want and its finish. The image below shows how the pulp is prepared.
Each fibre in the blend does a different job. Bamboo has long fibre that adds strength, bagasse helps give a smoother surface, and recycled paper fibre forms the base of the mix. The fibre is ground in water until it breaks down into a smooth slurry, so it can be drawn onto the mold evenly. Grinding time matters here, because fibre that is under-ground leaves a rough, uneven surface, while fibre that is ground too far loses length and the part becomes weaker. Screening then removes debris and oversized fibre bundles that would leave marks or thin spots on the part.
The point that shows up most in the finished part is slurry consistency, which is the amount of fibre carried in the water. It is held steady so that every cycle forms the same wall, because a slurry that is too thin forms a thin and weak wall, and one that is too thick makes the fibre lay unevenly. The slurry is also kept moving in the holding tank, so the fibre stays evenly mixed and does not settle before it reaches the forming mold. Depending on the project, additives such as water or oil resistance can be mixed in at this stage, which suits packaging that holds food or moist products, and we confirm any requirement of that kind at the specification stage.
07. How Does Forming Shape the Pulp?
Forming gives the fibre its first shape. The forming mold is lowered into the slurry and vacuum is applied through the mesh. Water passes through and the fibre stays behind, building up on the mesh in the shape of the mold. The result is a wet preform that already looks like the finished part.
Two parameters define the wall: the vacuum holding time and the fibre concentration in the slurry. The longer the vacuum is applied, the thicker the wall gets. Both parameters are adjusted so that wall thickness meets the requirements stated in the design throughout all its parts. At this stage, the preform is wet and flexible, which is the reason why wet press is used instead of an air drying process.
08. How Do Hot Pressing and Drying Finish the Shape?
Hot pressing is the stage that makes wet press what it is. The two halves of the heated hot press mold close on the wet preform, and the remaining water is pressed out and dried under heat and pressure in the same step. A single press typically takes around two minutes, depending on the wall thickness and the fibre. The press does three things at once.
It determines the shape. The preform is squeezed between the mating dies, so the part assumes exactly the shape of the tooling, including cavities, ribs, and all other details. It provides the surface. The fibres are squeezed by highly polished and heated surfaces of the tool, resulting in the smooth even surface which is characteristic only of the wet pressing process. It adds the strength. As a result of heat and pressure, the fibre becomes densely compacted, and therefore the wall becomes very stiff although being quite thin.
The temperature, the pressure, and the time are determined by the part, since the thick wall requires more time to dry off, and the part taken out of the press being too moist will not maintain its shape. The part is taken out of the press completely dry and rigid and is ready for trimming.
09. How Is the Part Trimmed and Finished?
After the wet pressing process, the part still has an irregular edge, caused by the additional fibre accumulated on the edges. The image below shows how the part is trimmed and finished.
A trimming die cuts the part to the exact outline and trims off the additional edge.
Finishing is about the details a customer sees and feels, and most of them are agreed at the design stage. The surface comes from the tooling, because the polished, heated mold faces leave a smooth, matte surface, so the inside of the pack looks as considered as the outside. Because the tool makes the surface and it is not applied afterwards, it stays the same from the first part to the last. Any embossed or debossed detail is built into the mold, so a logo or pattern cut into the mold surface is pressed into every part during hot pressing and does not depend on a separate step. That is also why it has to be decided before the tooling is made, because adding or changing it later means changing the tooling.
The edges are trimmed clean, and loose fibre is removed along the cut, so nothing is left to shed against a polished product such as a screen or a glossy casing, and the outline matches the dimensions in the design so the part sits flush inside the box. Packing is the last step, where finished parts are counted and packed dry, so they keep their shape on the way to you. Because molded pulp is a fibre material, we also ask where the parts will be stored, in case humidity is a concern.
10. How Do We Check Quality Before Delivery?
Quality checks run through the production run, and each one compares the part against the product and the prototype you approved. These are the points we look at.
- Fit: the part is checked against the real product, so it seats in one position without being forced.
- Wall consistency: the walls are checked for thin spots and uneven fibre spread.
- Edges and surface: the trim is clean, the surface is smooth and there are no wrinkles or loose fibre.
- Dimensions: the outline and depth are checked against the approved design.
- Dryness: the part is dry and rigid before it is packed, because damp parts lose their shape.
- Consistency across the run: parts taken at different points in the run are compared with each other and with the prototype.
- Load and handling: for heavier or fragile products, we agree with you how the packed part should be checked under the weight of the product and through handling.
Most problems in molded pulp have a recognisable cause, and most can be prevented at the design or tooling stage. This table shows the common ones and how each is controlled.
| What can go wrong | Common cause | How it is controlled |
|---|---|---|
| Wrinkles or warping | Uneven drying or pressing | Heat, pressure and time set to the wall thickness, and a tool surface that presses evenly |
| Thin or weak spots | Uneven fibre build up, often at sharp corners | Rounded corners in the design and steady slurry consistency |
| Ragged edges | A worn trimming die | Dies kept sharp and edges checked through the run |
| A loose or tight fit | A cavity that does not match the product | The product test fit and the physical prototype, before the tooling is made |
| Marks on the surface | Debris in the slurry or a worn mold face | Screened pulp and tooling inspected between runs |
| Parts that soften or distort | Moisture picked up in storage | Parts packed dry and kept dry until use |
11. How Does Molded Pulp Manufacturing Fit Into Our Seven Stages?
Every project we make moves through the same seven stages. For molded pulp, the manufacturing steps above sit inside them, which is why the early stages carry so much weight.
Whether tooling has to be built is what separates a first run from a repeat order, and it is the biggest single influence on the timeline.
| Factor | First run | Repeat order |
|---|---|---|
| Tooling | New tooling is built to the approved design | The existing tooling is reused |
| Reference | The physical prototype you approve | The approved part from the first run |
| Timeline | Includes the tooling stage | Can move faster, as the tooling stage is not repeated |
| Changes | Settled in the design, before the tooling is made | A change to shape or logo means altering or remaking the tooling |
Our lead time is ideally 3 to 6 weeks. The initial production involves tooling while the reordering process uses the same tooling and would take less time. The minimum order quantity for molded pulp is 30,000 pieces and above. Our guide to the custom packaging manufacturing process shows the same seven stages across everything we make.
12. What Should You Send Us to Start a Molded Pulp Project?
Your side of the sequence decides how quickly we can start the product test fit. This is what to have ready.
- The product: the real product or a sample sent to us, so the test fit is done on the actual item and not on a data sheet.
- Weight and fragile points: the weight of the product and any part, such as a screen or a lens, that needs extra clearance.
- Accessories: every cable, charger, manual or insert that needs its own space in the part.
- The box around it: the structure the part sits in, such as a rigid box, a corrugated box or a cardboard box, and how it opens.
- Quantity: the number of pieces for each design, and whether you need all of them at once or in stages.
- Details for the mold: any logo or pattern to be embossed, since it has to be built into the tooling.
- Storage conditions: where the parts will be kept, so we can tell you if humidity is a concern for a fibre material.
- Delivery and approver: the address and date you need the parts, and one person who can sign off the prototype quickly.
13. Why Choose PT Print for Molded Pulp Manufacturing in Malaysia?
We make the whole pack for an order, so the molded pulp part, the box and the outer carton are planned together.
- 40 years of experience: we have made packaging for over four decades, so the design and tooling decisions that decide a molded pulp run are ones we have made many times.
- Wet press molded pulp: a smooth, finished surface with thin walls and sharp detail, made for presentation packaging. You can see the range on our pulp mold page.
- One manufacturer for the whole pack: rigid box, pulp mold insert, corrugated box and cardboard box, with the fit of every piece checked side by side.
- A set seven stage process: a product test fit, a physical prototype and your approval come before anything is produced.
- Certified quality: we hold ISO 9001:2015 and ISO 14001:2015 certification.
14. Conclusion
The molded pulp manufacturing process is a chain, and every stage depends on the one before it. The design and the tooling are settled first, then the pulp is prepared, formed, hot pressed, trimmed and finished, and the parts are checked against the prototype you approved. Send us the real product, the box around it and the quantity for each design, confirm any logo or detail before the tooling is made, and allow for our ideal lead time of 3 to 6 weeks.
Need molded pulp made for your product?
Send us your product, the box it sits in and the number of pieces for each design, and we will take you through the test fit and prototype before anything goes into production.
Talk to Us About Molded PulpFAQs
What is the molded pulp manufacturing process?
The molded pulp manufacturing process turns fibre and water into a shaped, rigid part. It runs through design, tooling, pulp preparation, forming, hot pressing, trimming, finishing and quality checks. In wet press, the formed pulp goes straight into heated tooling, which sets the shape and gives the part a smooth surface.
What is pulp mold tooling?
Pulp mold tooling is the set of metal molds that gives the part its shape. It includes a forming mold with a mesh surface, a hot press mold in two halves and a trimming die. The tooling is machined for one design after the fit is confirmed, and it can be reused on repeat orders.
What is the difference between wet press and dry press molded pulp?
In dry press, the formed pulp is dried first and then pressed, which gives thicker walls and a rougher, eggshell style surface. In wet press, the formed pulp goes into heated tooling while still wet and is pressed and dried in one step, which gives thinner walls, sharper detail and a smoother surface. Wet press is the method we use.
What fibres do you use for molded pulp?
Our blend draws on bamboo, bagasse and recycled paper fibre such as old corrugated containers. We confirm the fibre with you at the specification stage so it suits the product and the finish you need.
How long does the molded pulp manufacturing process take?
Our lead time is ideally 3 to 6 weeks, depending on how quickly specifications and design are confirmed and whether it is a first run needing new tooling or a repeat order on tooling that already exists.
What is the minimum order quantity for molded pulp?
The minimum order quantity for molded pulp is 30,000 pieces and above, which is higher than for our boxes. Tell us your expected volume for each design at the start so we can plan the tooling and the run.
How is a molded pulp part designed?
We start from the real product, its accessories and the box around it, and check the product against the dimensions in a product test fit. Only then do we design the part, with draft on the walls, rounded corners, ribs where movement needs to be taken up and a small clearance around the product. A physical prototype is made and approved before production.
Is molded pulp packaging recyclable?
Molded pulp is fibre based, so it can go into paper recycling where those facilities exist. Collection rules differ from place to place, so check what is accepted in the market where the packaging will be used. You can read more on our sustainability page.
Can a molded pulp part be changed after the tooling is made?
A change to the shape usually means changing or remaking the tooling. That is why we confirm the fit on a product test fit and a physical prototype, and why nothing enters production until you approve it.