4 Reasons Why a Heated Bed is Needed With a 3D Printer


Heated Bed Stove Fire

Out of the many components of a 3D printer, the heated bed is one that doesn’t get too much attention, even though it serves a very important purpose. Without an efficient heat bed, prints will go from successful, high quality prints to stringy, warped, tacky-looking prints. That’s why I put together 6 reasons why your heated bed is recommended with your 3D printers.

Heat beds are needed for great print quality and layer adhesion throughout the print. They work by keeping the extruded material at it’s optimal temperature which stops common problems that many people experience when printing. Many prints are turn out bad due to not using heated beds.

Heat beds work extremely well to combat these problems, but they are always a better solution when combined with other techniques to improve temperature retention and layer adhesion. Below are 6 reasons why a heated bed is recommended with a 3D printer.

1. Prevents Prints From Warping

Warping is a common problem which is when the edges of your printed material cools down at a different rate compared to the rest of the material. When a hot, expanded material is extruded onto a cold, contracted material, it results in stresses in the material after the new layer cools.

This causes the cooled plastic to warp upwards and change the look of the print.

It then builds up over several layers which causes bending stresses which attempt to lift the edges of a print off the bed. It’s an issue which many people experience.

To prevent warping we will need to minimize how much cooling the previous layer does before the next layer is extruded.

There are two ways a heated bed prevents materials warping:

  1. It heats up the surface temperature to a point where the print will stick better.
  2. Through radiated heat which keeps extruded materials warm throughout the print above the surface.

The biggest factor in how much a print is going to warp is the difference between something called the glass transition temperature (Tg) and the cooled down temperature during a print.

In simple terms, the glass transition temperature is the temperature range where the material changes properties from being firm to a rubber-like state (not melted), measured in stiffness.

PLA has a low Tg of 122 F (50C). With an unheated bed it would cool down to room temperature, being roughly 68 F (20C).

ABS, on the other hand, has a Tg of 212F (100C) so if it cools down to room temperature, the big difference in temperature change is bound to cause warping.

It’s important to bear in mind the properties of the material you are printing. They handle temperatures very differently so some materials will experience issues more than others.

A heated enclosure/chamber works by keeping your printing environment at a higher temperature 140-176 F (60-80C) so you will end up with the same temperature difference of roughly 86F (30C).

It would be hard to count how many prints have been ruined by warping. That’s a lot of plastic wasted and turned into junk, so a good quality heated bed can save you a lot of time, money and frustration. Warping happens more so with thinner parts of plastic so it could depend on your models.

It’s important to note that heated beds aren’t a complete solution to solve warping issues. They will work to lower the chances that your prints warp but when used in conjunction with other methods, it works more efficiently.

2. Retains Temperature of the Printing Space

Heated beds used to be a rare addition to 3D printers which resulted in printed objects cooling very quickly once the printing process started. In today’s 3D printing culture, heated beds are more commonplace.

They do a good job of retaining temperature of the 3D printing area to help the materials perform at their best. This results in printed objects cooling at a much slower rate, and reduces stresses on the material.

A downside with some heated beds is that they don’t always cover the full size of the bed and tend to be a smaller pad that fits underneath your print surface. This can create uneven temperatures on your printing surface so it’s important to test the temperature of your surface all around, and make sure it’s not concentrated around the sides or middle.

Some temperature readings can give you inaccurate numbers due to parts of the print surface taking more time to heat up. You can combat this by waiting 10 minutes or so after your reading is giving you the correct temperature just as a counter-measure.

Another solution that some people use to retain temperature in their printing space is a heated chamber or enclosure. They work a similar way, but instead of the surface being heated, the whole enclosure is heated.

Heated chambers or good enclosures work well with high-temperature plastics, because they increase and maintain optimal temperature levels above the heated bed in order to help prevent prints warping.

Keep in mind that constant running heat can get costly, and more care needs to be taken to ensure things are running smoothly. Some parts that you have in your printer may not run so well at higher temperatures as they can cause stress on some electronic parts, resulting in a shorter lifespan.

The upside here being, when your printing environment is insulated, it should reduce your running costs due to not having to add more heat. It also keeps your temperatures even which should reduce the cooling at the edges of your enclosure.

3. Helps First Layer Adhesion

This step also ties in with warping within materials. Your first foundational layer of material is very important to the rest of the printing process.

Without good first layer adhesion on the build plate, your prints will not stick very well and it will increase the chances of a print failing. When you have good adhesion it also works by reducing the warping of the material.

3D printers have print surfaces which are very durable but also quite smooth, which can cause materials to slide rather than stick to the surface.

Using a heated bed reduces this sliding issue by giving the material an optimal level of adhesion to the surface. It relates back to the glass transition temperature where materials are in their more ‘rubber-like’ state so have an easier time sticking down.

This is especially true with adhesion using ABS and similar thermoplastics because they have a higher glass transition temperature. After materials are extruded from the extruder, they have nothing in particular to stick down to when put onto smooth surfaces. This means warping becomes enhanced, resulting in reduced adhesion to the print surface.

The fix here is to use build surfaces as well as substances that boost your adhesion. Many people out there use items such as painter’s tape or Kapton tape to improve first layer adhesion.

Depending on what combination of build surface material and filament type, you can have a easy or hard time getting your first layer adhesion. Over time, you’ll learn what works best with some trial and error. Many bed surfaces do tend to change it’s shape when there are temperature changes.

Metal heat beds are great because of it’s property of retaining heat and spreading easily. This is because metal has a high thermal conductance. Some metals are the opposite, such as copper and steel, which take more time to heat up and cool down.

Most metals actually expand somewhat when they are heated, so you should be aware that this change in shape of a metal heat bed can damage prints. The thinner a metal print bed is, the more is it susceptible to expanding and bending.

The best thing to do is experiment with different temperatures, increasing and decreasing them in increments until you have many successful prints.

Making sure you’re using the correct temperature on your heated bed will ensure that the first layer(s) of your print stays warm and doesn’t contract too much from cooling. There are guides out there that will tell you what temperatures are best for a specific material.

First layer adhesion issues can sometimes be solved by increasing the temperature of the heated bed, but if this occurs, there’s usually an underlying issue you need to take care of such as bed levelling.

4. Assists in Print Removal

Heated beds are great for helping remove your finished prints from the bed. So many 3D printer users have issues getting their prints off the bed, to the point where they either scratch their surfaces using harsh tools, or even worse, accidentally cut themselves using too much force for something that should be easy.

With most PLA prints, especially the smaller ones you should be able to remove prints without the use of a heated bed due to the nature of the material. Your medium size PLA prints may require some removal tools to successfully get the print off the surface. With larger prints a heated bed should work wonders in helping you remove it because they can be quite tough to remove, due to the surface area adhesion being far higher than normal.

The first thing I’d advise when removing finished prints from the surface is to let the heated bed cool down completely. If you’re lucky, once the material has cooled down, your prints can simply pop right off the print surface with ease.

If this doesn’t work you can do the opposite by cooling the area with a fan or a cool pack. Putting the build plate in the fridge or freezer for a short time should also assist with print removal.

I’d say it’s much more worth it in the long-run having a heated bed and avoiding common problems people have. It will save you time, effort, money and a lot of stress!

When a material has cooled down, it gets back to it hardened state rather than it’s ‘rubber-like’ state and shrinks abit, making it easier to remove from the print bed.

If you are printing directly on glass, letting your heated bed cool to room temperature should do the trick in lifting prints off without effort.

Sometimes prints can still get stuck down even after cooling. In this case, some people have found it helpful to heat the bed back up then try to remove the print.

Heated Beds Vs Filaments

Heat-beds for the most part, keep the bottom of the print warm. Enough distance from the build plate (1cm) and the print will be closer to the ambient temperature than the bed temperature. Some materials hold heat better than others such as PLA so action isn’t always needed. Some brands of filaments perform differently at temperatures so keep this in mind.

The three main filaments:

ABS

ABS has a tendency to warp and really doesn’t bode well with breezes or temperature changes, so a heated bed is highly recommended when printing it. A heated bed along with an enclosure will be a great solution to these problems, and should help you get your successful prints.

Certain print surfaces are better than others to prevent issues such as warping, but the nature of ABS means that a heated bed does a great job in keeping prints under control.

PLA

The most widely used filaments is PLA because of many reasons, one of which being its low tendency to warp and generally being easy to print in many environments. PLA doesn’t necessarily need a heated bed to do it’s job, but bigger prints can cause trouble, by not sticking down too well if not printed on a heated bed. As previously mentioned, it will help out with warping issues and many others, so it’s definitely beneficial but not required.

PETG

This material is described by many to have the printability factors of PLA while incorporating the strength and durability of ABS. It does however have stringy properties and a higher chance of warping compared to PLA. With PETG a heated bed is something that I would recommend, as it should help prevent warping.

Extra Tips for Heated Beds

Having a glass bed with a sticky substance such as glue or hairspray can be enough to help extruded material stick to the print bed. Glass beds don’t have the best insulation so it requires more heat to get it to the set temperature, but they are great for removing prints once they have finished.

There are techniques that are used to get prints to stick better to the print bed such as rafts or brims, but these won’t be as effective without having a heated bed.

There are many different types of heated beds, some that come in kits, some that are different materials but they all serve the same purpose.

A good thing to remember is that the temperature that you set your bed and your bed temperature may not always be the same. It depends on the construction, assembly, quality of the heater and temperature sensors so it can differ.

Heated beds do require a lot of power so it can be relatively costly to have running all the time. You want to make sure your heated beds are installed properly, because improper installation can lead to burned wires and connectors.

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