Molded Fiber 101
Tooling
A: There are certain additives that can be used with multiple benefits including assisting in releasing product from the mold. The sticking issues are most typical on the press tools and not in the molding/forming tools. Release agents sprayed onto the tooling (either manually or built in as part of your machine system), can be very helpful in releasing problematic products. One should always try and understand what is causing the issues with releasing to better address the problem. Whilst not limited to the following, it could be poor tooling alignment, poor tooling design with problem angles or depth, tool temperature, unfavorable raw material being more prone to producing “stickies”, dirty or poor tool cleaning and many more.
A: Typically, your tool will need to land up facing up so that the transfer tool can pick it up off the forming tool and then deposit it down onto a bottom press tool, so much depends on the geometry of the tool/product and whether you have deep “wells/ dams”. Some forming systems allow for a tooling platen holding the tools to rotate through 180 degrees allowing for a “tool facing down” before submersion and rotating again (“tool facing up”) before transfer. These machines can also then be submerged “tool up and returned without rotating to transfer “tool up”. The issues with forming on Thermoform are unlikely to be different, in principle, to conventional forming.
A: Temperature is the last resort for drying a thermoformed product. One should first off spend every effort in reducing the moisture content of your wet product before placing it on the heated press tools. Pressure is vital and particularly controlling the pressure/time curve on closing. Most simple TF machines will not allow you to manipulate in milliseconds, the closing pressure. Heat, whilst the most impactful in reducing cycle times, comes with a host of consequences. Most TF press tools are aluminum and heat softens them chronically and leads to damage and high wear. Extreme temperatures also aggravate the “burning” of “stickies/ residue” onto the press tools which in turn cause fiber off the next product to stick and further aggravate the situation. So, try ensuring you have every other moisture reducing trick covered before heading for the increase temp button.
Molding
A: In a very generic answer which ignores many product specific requirements; cleanliness (no plastic, sand, metal, wet strength contaminants) and freeness of your fibre are very important. Conventional is way more forgiving on cleanliness but only to a point. Since TF has very high cost, soft aluminum pressing tools, which do not like raw material with abrasives of metals, nor plastics even in micro form which will stick to your heated press tools and quickly stop the Thermoformer. A conventional machine will also accommodate a lower freeness fibre than TF will.
A: This could be answered from so many different perspectives, but I will answer it from a MF manufacturing point of view. Conventional machines with high volume outputs are more able to compete with Polystyrene products on price but not necessarily on aesthetics unless after pressed. There are big issues with after pressing which typically require high volume and infrequent product design changes. Egg packaging is typical of a MF product which has easily displaced polystyrene and outperformed it on many levels.
So many of the polystyrene products we currently identify with are in the foodservice industry (food clams etc) and whilst Moulded Fibre and particularly Thermoformed MF, easily competes aesthetically, the same cannot be said for pricing. Our industry’s biggest challenge here is the ratio between capital cost vs output. We are seeing a plethora of equipment manufacturers in plastic thermoforming or injection moulders now converting to Molded Fibre. The issue is that “typically” the pulp version of the machine making the displacement product but only in pulp, costs the same to buy as it’s plastic producing counterpart but puts out only around 10 to 20 percent of its plastic/ polystyrene counterpart. Again, this is a very broad comment easily identifying with food service products and could be different for many other products. So, getting our pulp Thermoformed cycle times down is the single biggest influence we can have in reducing costs and being more competitive in our bid to displace polystyrene. (And yes, legislation, after all of these decades, is coming to our aid along with better informed consumers).
A: Temperature is the last resort for drying a thermoformed product. One should first off spend every effort in reducing the moisture content of your wet product before placing it on the heated press tools. Pressure is vital and particularly controlling the pressure/time curve on closing. Most simple TF machines will not allow you to manipulate in milliseconds, the closing pressure. Heat, whilst the most impactful in reducing cycle times, comes with a host of consequences. Most TF press tools are aluminum and heat softens them chronically and leads to damage and high wear. Extreme temperatures also aggravate the “burning” of “stickies/ residue” onto the press tools which in turn cause fiber off the next product to stick and further aggravate the situation. So, try ensuring you have every other moisture reducing trick covered before heading for the increase temp button.
- A: Capital cost per output is the single biggest differentiator between the two. A typical comparison would be (and this is very broad) , buying a Thermoformer or a Conventional machine from the same company and spending the same capital, the conventional (excluding after pressing and printing) would produce about 7 x more per given time frame than a Thermoformer.
- A: Tooling cost per ton of output per day on TF could be about $100k vs a conventional putting out 7 ton per day costing the same $100k for all of its tooling. A small 2 ton per day conventional could tooling as low as $25k
- A: TF machine whilst able to run on thermo oil (many manufacturers will not venture into this due to the ongoing oil leak issues) typically runs on electrical energy whilst conventional machines can run their driers on many different options such as gas, steam, biomass etc.
- A: There are many more considerations between the two but too vast to answer in this forum.
A: The items that influence solids content off the moulder include but are not limited to the following: Fibre freeness, pulp/water temperature, cycle time (obvious and least attractive), drainage aids, efficiency and capacity of your vacuum system, tool design (back-end drainage) and screen wire selection. Understanding all of the aforementioned elements influencing solids will lead you to determining which of them you have scope to improve on and which will give you the best return on your cost and efforts.
A: The diversity of water treatment systems is such that this cannot be answered on this forum. Typical water usage in a system that does filter and recover/reuse all of its systems’ water will be limited to that which is flashed off in the drying process, this being pressing in Thermoforming or the drier in a conventional system. Assuming you were running an underwhelming solids content of 25% off your moulder (TF or Conventional), in drying you would flash off around 3L of water for every Kg of product produced. (This is not a science lesson on splitting hairs between incoming raw material moisture content and outgoing 6 to 8% product moisture, it’s a simple arithmetic take on it). There are many efforts taking place which strive to recover, through condensation, evacuated moisture during the drying process, this will obviously result in lowering the amount of water lost to atmosphere and hence a lowering of the typical 3L/Kg.
Drying
A: In my 30 years in this industry and with many personal investigations into this in various countries, I have not been able to get the economics to stack up using electricity in big conventional driers. This is not to say that technology will not change this situation.
A: This is a topic that would best be dealt with in some future collaborative workshop rather than in a Q&A for the website. My best practice is to run frequent (manual) moisture profiling in the different zones in the drier. This needs to be done on all products in order to optimize drier settings for energy consumption and in order to manage shrinkage of the product.
A: Not any easy one and not able to address it on this forum. There are many steam fed driers that are being powered by biomass from annual agricultural crops which are clearly renewable.
Miscellaneous
A: Unfortunately, not. This industry has played its cards close to its chest for its entire relatively short history. Snag a rare, retired fella 😊. Join IMFA and work flat out at building your network.
A: The East has long been producing and selling top quality non wood fibre for use in the Thermoforming industry. This has been mainly aligned with Thermoformed products being made in big volumes in the East. With developments in non-wood pulp production outside of Asia in recent years, along with current significant investments in the likes of USA, Australia and elsewhere, I see the global supply of pre-processed fibres actually being less of an issue than the ability of the industry to turn on viable, quality Thermoformed machine capacity. There are also significant developments with Thermoformers using virgin wood fibres which will further feed into the TF raw material needs.
Fiber
A: Yes, many applications of wood and non-wood fibre being mixed.
A: The single biggest manufacturing challenge is the different shrinkage aspects of these various paper types. ONP may shrink as little as 2% and DLK as much as 7%, (I have used virgin waste stream kraft from a next-door paper mill and the shrinkage was as high as 11%). Your tooling (and assuming that if we are talking about OCC, DLK & ONP then we are talking conventional and not Thermoformed) is designed such that shrinkage through the drier is compensated for in the tool design. If you start introducing different fibres you will most certainly influence that to a point of serious consequence on dimension and denesting, also transfer out of your tooling.
A: Since refiners are typically expensive bit of equipment and the refiner plates are very expensive consumables, you cannot be feeding refiners things that could wear or damage the plates. There are many different levels and costs of cleaning equipment for pulp preparation, but the following would be typical of an upstream refiner in a moulded fibre manufacturing operation: Some type of screen (Johnson, Kadent, Poire, custom made) for removing larger non fibre elements. Centrifugal cleaners for removing smaller but heavy (sand, glass, etc.) elements and then a magnetic trap for catching as much metal as possible, like staples from OCC etc.
A: Yes, you can but they are very limited in angle and directly influenced by depth. There are many tooling specialists in our industry that can advise on specific draft angles for specific applications/designs.
A: Yes, you can. It is not common nor widely understood but it is happening at the pointy end of our industry.
Chemical Additives
A: This is such a broad question that cannot be answered in this forum. Discussing your product performance requirements with a consultant of paper chemical supplier would most certainly have you going in the right direction.
A: Retention aids are very common and assist in many aspects of manufacturing, some of which are keeping your back water cleaner for reuse, improved retention of dye/colorant, improved solids content, and higher fibre yield.