HOW TO PREVENT HUMIDITY

AFFECTING 3D PRINTER FILAMENTS

AUTHORS: STEVE JONES AND DAVID FOLLEY

Copyright: Westside International Ltd

Introduction 3
Background information 4
Why do we need to use dehumidifiers 5

in 3D printing?

Different types of dehumidifiers 6
- Ventilator/Heat pump/Refrigerant Dehumidifiers 6
- Desiccants bags dehumidifiers 6
- Desiccant Dehumidifiers 6
- Solid State Dehumidifiers 7
  - How does a solid-state dehumidifier work? 7
- What to consider in choosing the way to 8

dehumidify your 3D filaments?

Dehumidifier type comparison chart 9

Conclusion 10

1.0 Introduction

One of the largest factors in setting up and running a 3D print farm is the overhead costs. These are increased mostly in the form of failed prints and wasted energy costs.

Increase profit and throughput by decreasing the failure rate due to filament problems and keeping the energy costs for this trade-off in check with a simple humidity control solution. Humidity can drastically effect the quality of 3D printing. These effects can be multiple but the most obvious is pitting of printed surfaces. The main source of humidity affecting a 3D

printing process is in the storage of 3D printing elements or filaments as they are commonly known. These are normally stored in an airtight enclosure. These enclosures are not to be confused with the enclosure 3D printers are sometimes stored/used in. Condensation in filament storage enclosures can be extremely hard to control.

2.0 Background information

Before reading this whitepaper, it is advisable that you understand the following basic terminologies to understand the whole processes involved:

2.1 Humidity

Humidity is the ratio of water vapor in the air to the maximum amount of water vapor in the air that could be present if the air was completely saturated at a given temperature. Humidity therefore is dependent on the air’s temperature. A crucial point that is often forgotten or misunderstood about relative humidity (RH) is that the “relative” part is referring to that “given temperature” from the definition. Therefore, humidity is relative to temperature. Meaning that the warmer the air mass, the more water vapor the air can hold.

Humidity is expressed as a percentage where 100% relative humidity (RH) would represent the maximum amount of water that is able to be held in the air at a given temperature.

2.2 Dew point

The dew point is where moisture in the air condenses to form water droplets. The Dew point of a given body of air is expressed as the temperature to which air must be cooled to become saturated with water vapor. This temperature depends on the air pressure and water content of the air. A Dew point temperature is never greater than the air temperature. This means if the air cools, moisture must be removed from the air and this

occurs through condensation. This process results in the formation of water droplets. These tend to form on the coldest part of a container, window in a room etc.

The higher the relative humidity, the closer the dew point is to the current air temperature, with 100% relative humidity meaning that dew point is equivalent to the current temperature. In cases where the dew point is below freezing (0°C or 32°F), the water vaporturns directly into frost rather than dew. Where the condensation is ice, this is known as the frost point.

2.3 What is a Dehumidifier?

A dehumidifier removes moisture from the air. A major reason dehumidifiers are used is if the moisture in the air meets dew point, then condensation will start to form. For things like electronic devices or metal items stored in a display cabinet this can be catastrophic as the condensation can act as conductors and can create

short circuits or tracking faults leading to component failures. Dehumidifiers are used in lots of different applications such as matter preservation. In food if the moisture content is high, it will perish faster and will allow bacteria and moulds to grow. With bacteria, the majority require a relative humidity (RH) of 60% or more to grow, though some can survive and multiply in less than 20 percent RH. Even domestic items such as cameras and lenses should be stored in a dehumidified display case to ensure the camera lens is not fogged internally by moisture ingress, leading to mould. Therefore, the job of a dehumidifier is to remove moisture from the air when the humidity is too high. Many forms of dehumidifiers are available and correct selection is important.

2.4 What is a Humidifier?

A humidifier is the opposite of a dehumidifier. Its job is to add moisture to the air. If you have too low a moisture content items can also start to perish. An example ofthis is paper. If paper is kept in too low a moisture content it will start to break down the fibres holding it together. Paper needs to maintain a humidity level of between 30 – 50 percent. Too dry it will fall apart, too moist then it will start to bubble up and attract moulds.

Why do we need to use dehumidifiers in 3D printing?

To get the best print quality in 3D printing the biggest issue with humidity is the storage of the filaments. Most filaments are kept in airtight enclosures, but the moisture level of the air is whatever the air moisture level was when the enclosure was closed. Typically, the RH in an average house is between 40 – 80% usually dependent on whether air conditioning is being used. In commercial buildings where air conditioning is used it is normally air conditioned keeping it to 40-60% RH. It does not matter what type of 3D filament you are using be it Nylon, RH, PVA, PA, TPU, PAHT, PLA, PETG, or ABS, they all will absorb moisture to some degree.

3D filament manufacturers normally recommend that you store filaments below 45% relative humidity (RH), and state quite clearly that at humidity levels above 55-60%, you will certainly see visible problems, and even down to 45% issues will occur. These problems that are encountered are quite clear to see in most cases. Filaments that have absorbed moisture tend during the extrusion process to “bubble” and “warp” more when they are heated, as the absorbed moisture heats up and forms steam pockets which are released from the molten filament material, disrupting the smooth flow of the molten filament.

Bubbles can then manifest themselves as irregularities or voids in the printed object, affecting its overall quality and structural integrity. Warping, which is also due to high moisture content of the filament causes uneven cooling rates within the printed layers. This happens as moisture makes the filament cool unevenly, with some sections contracting more than others, leading to distortions or deformations in the printed object. This issue becomes very apparent when sections of the print detach or lift from the print bed, resulting in a warped or distorted final product.

The big question now is how to stop filaments being exposed to an excess of moisture, as even in air-conditioned rooms where the RH is usually much more than 45-55%. A simple solution is to use a dehumidifier. Todehumidify a whole room is extremely expensive due to the size of the dehumidifier needed and the energy consumption required, so the solution is to use a dehumidifier on the storage cases of the 3D printing elements. The next question is what type of dehumidifier should be used.

4.0 Different types of dehumidifiers

There are 4 main types of dehumidifiers.

Ventilator/heat pump types, commonly known as refrigerant dehumidifiers
Desiccant bag dehumidifiers
Desiccant dehumidifiers
Solid-state dehumidifiers

Each has a different method of removing moisture and knowing the difference between each variant will help you decide which one would best suit your needs to help protect your equipment.

4.1 Ventilator/heat pump/refrigerant dehumidifiers

A heat-pump or refrigerant dehumidifier, as they are also known, uses the same process as a domestic refrigerator. The refrigeration process cools a metal plate on which moisture from the air condenses. A fan constantly draws the air through the dehumidifier and over the cool metal plate(s) and all the time more of the moisture condenses onto the plate and drips into the dehumidifier’s water tank. Eventually the relative humidity in the enclosure is reduced to a normal level and the unit will then switch itself into standby until such a time as it is required again.

Refrigerant dehumidifiers are most effective at typical room temperatures and their performance declines dramatically in cooler conditions. The common reason for this is the formation of ice on the metal cooling plates (coils). This freezing can occur at any temperature from about 65°F/18°C downward. A refrigerant dehumidifier can operate effectively at lower temperatures but requires higher performing components and additional features to achieve this, making it more expensive. So, if you think your dehumidifier may often be used in an application

which often has a fairly low temperature then this may not be the best option.

4.2 Desiccant bag dehumidifiers

Desiccant dehumidifiers absorb moisture from the air using a desiccant. A desiccant is a material that absorbs water and will be familiar to anyone who has ever found a small pack of crystals, labelled “silica gel”, packaged with a camera, computer, or some other product when you purchase these types of electronic products. Also known as desiccant dehumidifiers, they consist of hydrophilic materials, such as silica gel. Many desiccant dehumidifier units contain single-use desiccant-type cartridges, gel, and powders, which when laden with moisture need to be thrown away and replaced with a new desiccant.

4.3 Desiccant dehumidifiers

A desiccant humidifier uses the hygroscopic materials used in desiccant bag dehumidifiers but uses heating to reuse the desiccant. In a desiccant dehumidifier, a wheel consisting largely of the desiccant turns slowly through the incoming air stream and absorbs moisture. During the rotation cycle a proportion of the wheel is passing through a stream of warm air which “reactivates” the desiccant by driving off the moisture. This condensed water is then collected in the dehumidifier’s collection tank or automatically drained out via a tube from the back of the unit to the outside or via a drain etc. This type of dehumidifier tends to be smaller and lighter than the refrigerant type. Desiccant dehumidifiers can operate at much lower temperatures than a refrigerant type.

See table 5.1 for a comparison of different dehumidifiers.

4.4 Solid State Dehumidifiers

A solid-state dehumidifier removes moisture from the air by the use of electrolysis when a small voltage is applied to a solid polymer electrolyte (SPE) membrane. The membrane attracts moisture to an absorbent side, where it dissociates into hydrogen ions (H+) and oxygen. The hydrogen ions (not hydrogen gas) migrate through the membrane for discharging on the cathode (moisture discharging) side where they react with oxygen in the air, to form water vapour. Solid state dehumidifiers provide clean moisture extraction and low cost, maintenance free performance. One major advantage of solid-state dehumidifiers is that they are extremely compact and small, with the smallest devices being the size of a hazelnut.

4.4.1 How does a solid-state dehumidifier work?

PRINCIPLE OF DEHUMIDIFICATION

(Picture kindly supplied and technology rights owned by Ryosai Tec, part of the Mitsubishi Electric group of companies)

5.0 What to consider in choosing the way to dehumidify your 3D filaments?

When deciding which type of humidifier you need for your 3D filament storage case(s) you will need to consider the following questions:

How often will you open the storage case? If this is regularly then every time you open the case, you will basically reset the RH level in the case to the RH level of the room you are If you are opening the case regularly then desiccant bag humidifiers will fill and become useless very quickly.
How well sealed is the enclosure? If the door seals do not restrict air seepage and moisture ingress then you will need a dehumidifier that never fills to a maximum capacity, e. do not use desiccant bags or dehumidifiers that collect expelled moisture (need emptying).
Does the enclosure have air flow ducts? If yes, the RH level will fluctuate as air ingresses into the enclosure. Desiccants bags will not provide any long-term solution for this issue.
How often are you able to empty water collected? If you are leaving the filament storage cases for periods on their own, please remember that refrigerant and desiccant dehumidifiers collect all the moisture they expel from the air in collection tanks. These will need to be monitored and emptied when
Does the environment where you are storing the 3D filament cases need to be quiet? If you do not want to hear electro-mechanical noises, then you will only be able to use desiccant bags or Solid-state dehumidifiers as they make zero noise. Refrigerant and desiccant dehumidifiers do make noise which will increase as the machines get old and start to mechanically wear. Solid state dehumidifiers and desiccant bags do not wear out.
Do you want/need to be energy efficient? If being energy efficient is necessary due to government regulation or personal financial position, then solid-state dehumidifiers and desiccant bags are the best way forward. Solid-state dehumidifiers like Rosahl’s dehumidifiers use only 3 VDC and for smaller membranes use only 0.06 watts of energy. Disposable single-use desiccants are energy efficient, but if you have the type that can regenerate it takes a lot of energy to periodically dry out the crystals.
Do you have environmental or recycling requirements? For companies and individuals that have environmental and recycling requirements then refrigerant, most desiccant dehumidifiers and solid- state dehumidifiers will meet your needs. Due to the one-time use of desiccant bags the desiccants cannot be reused or recycled, and these compounds such as silica gels will just be put into landfill

5.1 Dehumidifier type comparison chart

Below is a simple comparison chart of dehumidifier types. Some dehumidifiers only reduce moisture but some like Ryosai Tec’s Rosahl solid-state dehumidifiers will actually humidify and dehumidify.

Refrigerant Dehumidifiers

Desiccants Bags Dehumidifiers

Desiccant Dehumidifiers

Solid-state Dehumidifiers

Initial Cost

High

Low

High

Medium

Energy Use

High

None

High

Very Low

Life Expectancy

Medium

Very low

Medium

High

Environmentally friendly

Medium

Very

Enclosure size

Large

Small

Large

Medium

Operating Temperature

Better in higher temperatures

Good at most temperatures

Good at low temperatures

Good at most temperatures

Waste

Water is collected in a drip tray

Water is absorbed into the material

Water is collected in a drip tray

None

Negatives

Needs tray emptying of water

Needs replacing often. No accurate indication of when full

Needs tray emptying of water

None

Dehumidify

Yes

Humidify

Yes

Size

Large

Small

Large

From micro-small to medium

6.0 Conclusion

In conclusion, one of the largest factors in setting up and running a successful 3D print farm is reducing the overall costs. These can be decreased by reducing failed prints, which saves money on wasted filaments and time but also saves wasted energy costs. An easy way to increase profitability and throughput by decreasing the failure rate due to filament humidity problems is with a simple humidity control solution. Based on the current known dehumidification offering that is suitable for 3D printer filament storage, solid-state dehumidifiers, such as Rosahl’s micro-dehumidifiers offer a compelling solution for effectively controlling moisture and humidity in filament storage cabinets and enclosures. This white paper has highlighted the numerous advantages of using solid-state membranes, including their compact size and low energy consumption.

By using solid-state polymer electrolyte (SPE) membranes, dehumidifiers such as Rosahl’s micro-dehumidifiers provide a waterless and maintenance-free option for drying enclosures. The absence of moving parts ensures silent and vibration-free operation, combined with their small energy and physical footprint enhances in a simple manner the reliability of 3D filaments in the 3D printing process.

Example of a simple dehumidification solution using a solid-state humidifier and powered by a USB-C PSU, produced by http://chip45.com

Footnote

Rosahl dehumidifiers are manufactured by Ryosai Technica, which is one of the Mitsubishi Electric group of companies.

For more information on Rosahl micro-dehumidifiers please contact internal-sales@micro-dehumidifier.com or visit micro-dehumidifier.com

7.0 Rosahl membrane product range

Rosahl membranes

Seven ranges are available depending on the type of installation and size of enclosure. They are:

PD4/5 Series – for dehumidifying enclosures up to 1 litre
PD2/3 Series – for dehumidifying enclosures up to 2 litres
RD Series – for dehumidifying enclosures up to 2 litres
RS Series – for dehumidifying enclosures up to 5 litres

Type MDL – for dehumidifying enclosures from 5 to 2m3
New M Series – for dehumidifying enclosures from 25 to 4m3
Enclosed membranes – pre-installed in a steel case for ease of mounting

Rosahl selection chart	PD4/PD5*	PD2/PD3**	RD3/RD4***	RS1/RS2****	MDL-3	MDL-5	MDL-7

Dehumidifying (grams/day)	0.042	0.084	0.084	0.21	4	8	16
Applicable volume	<1 litres	<2 litres	<2 litres	<5 litres	<0.5m3	<1m3	<2m3
Element terminal voltage	3V DC	3V DC	3V DC	3V DC	3V DC	3V DC	3V DC
Power consumption (W)	0.06	0.08	0.08	0.22	2	3	4
Dimensions (mm)	Ø 17 x 11	Ø 17 x 11	30 x 24 x 5.5	21 x 28 x 13 5	96 x 63 x 2.3	96 x 88 x 2.3	116 x 108 x 2.3
Weight (g)	0.9	1.8	1.8	3.4	20	25	50
Operating temperature	-10 to +50C	-10 to +50C	-10 to +50C	-10 to +50C	-10 to +50C	-10 to +50C	-10 to +50C
Notes	* Connector PD4 soldered PD5 push	Connector PD2 soldered PD3 push**	*** Mounting RD3 outside RD4 inside	**** Connector RS1 Soldered RS2 Push	Push connector with 50cm cable supplied	Push connector with 50cm cable supplied	Push connector with 50cm cable supplied

Enclosed membranes	S-5T1	S-7T1	S-10T1	Notes 1 The initial value at the temperature of 30°C and humidity of 60%. (The dehumidifying capacity of the membranes will degrade over time depending on the operating environment 2 The applicable volume is for a sealed, moisture-impermeable container, and may vary depending on the material of the container, state of sealing and required humidity. *3 The annual average power consumption in average conditions in Japan.

Dehumidifying (grams/day)	8	16	29
Applicable volume	<1m3	<2m3	<4m3
Element terminal voltage	3V DC	3V DC	3V DC
Power consumption (W)	3	4	8
Dimensions (mm)	130 x 111 x 30	150 X 138 x 30	185 x 168 x 30
Weight (kg)	0.4	0.5	0.7
Operating temperature	-10 to +50C	-10 to +50C	-10 to +50C
See Notes (right)

internal-sales@micro-dehumidifier.com

+44 203 286 8189

www.micro-dehumidifier.com

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