Case Study of the Use of 3D Printing

Industrial Applications

Date: 7/17/2018

Author: Mike Schoonover

Rev: 1.0

Overview

I started my foray into 3D printing by farming out jobs to various commercial printers. While the larger firms gave very professional results, the cost was about 20 times higher than what is typical for in-house printing. I still farm out any metal printing as the cost of those types of printers is prohibitive.

The small local "garage" print shops produced acceptable results at about 1/4 the cost of the big firms, but often had trouble with lift-off and warping for ABS parts. In addition, shipping or physical pick-up of the parts increased the turn-around time. As some of our prints now take 72 hours, the cost would also have increased dramatically over time.

I never wanted to own a 3D printer because I didn't want to have to learn all the intricacies required for success. I did a lot of research and for my first printer chose the Flash Forge Creator Pro Dual as it had the least number of complaints and only cost $900.00. I thought that we would have one or two parts which would be 3D printed and that most of our uses would be fixtures or test devices.

At first, we printed in PLA and then Innofil3D’s PRO1, which is a better form of PLA. The results were great, but PLA is biodegradable so use in the field resulted in some mushy parts...especially those exposed to water.

We switched to Innofil3D’s InnoPet filament and that is now our main material. In the future, we plan to print in Nylon and NylonX as well.

Learning Curve

Our first printer came with a blue pad for the bed. Prints stuck quite well...too well. A lot of twisting and scraping were required to remove the parts. This placed excess force on the build plate, which is by necessity a precision device. Since it was not easy to remove the build plate, the part had to be removed in place. We tried blue tape on the pad and on the bare metal plate with mixed success...lift off at the corners was frequent.

We purchased a third-party removable glass plate and then learned about glue; our problems mostly disappeared. The glue we use comes in stick form from Staples, but any similar Polyvinyl Acetate (PVA) glue should work. By accident, we found that Hydrogen Peroxide dissolves the glue quite quickly...faster than alcohol. Most prints pop off after the glass cools. For the difficult ones, a few minutes in the freezer will allow them to be separated easily. One main benefit is that the glass is easily removed from the printer so it can be handled in the open.

The Farm

The first 3D printer you buy is great...the second one is even better...but the third one makes you a farmer. I purchased a larger printer, the Ultimaker Extended, a few months later. This allowed us to make larger single-piece prints, but it was not an absolute necessity. Smaller prints can be joined to make larger pieces, so we could have done most things in the smaller printer. Another advantage of making small prints is that failures don’t cost as much time and material to correct.

The longest print we ran took 72+ hours. Most of the parts took 4 hours, but more and more we were seeing 17 hour runs. Both printers were running day and night, so we purchased another Creator Pro Dual as we had some upcoming projects and needed to increase production. The trick is to keep at least one printer somewhat available, running short parts at 4 hours or less, so you can insert a quick part into the queue when needed.

But is it Useful?

Originally, I had no idea what we would make with the printers. I figured we would print a couple of things and then they would sit in the closet gathering dust. I was so wrong. The obvious candidates for 3D printing are any parts used internally to the company, such as machining fixtures, assembly aids, and test jigs. The second tier are parts used inside of products where blemishes are inconsequential, such as wire routing gadgets and component mounts. The third tier are panels on the back of the unit where a perfect finish is not required.

For industrial equipment manufacturers, the fourth tier of 3D printing extends to virtually any bracket or panel. As these machines often use roughly finished aluminum parts for such things, the 3D printed parts are often better in appearance.

For uses where the part is to be visible in a commercial quality product, the parts must usually be sanded and painted. The time to print combined with finishing time can make this usage less economical than other methods, especially in large quantities.

Some of the best printers can produce a finish suitable for lower-end commercial products. In my experience, I almost always end up with a blemish somewhere on each part. A hiccup on one layer will cause a ripple for several layers above. In addition, holes or text in the part usually cause unattractive ripples all the way to the edge of the part due to the manner in which the extruder paths are calculated.

As it turns out, at least three times a week we say the phrase, “Let’s 3D print a gizmo to hold this gizmo at this angle”. One amusing use (from an engineer’s point of view) is the replacement of a super hard to machine high-temperature material in a precision device. We had documented the part in our cad program with the intention of having it machined, but someone printed it in InnoPet just for giggles (we need all the giggles we can get). Since it was easy to shape and tweak, it ended up on the machine. And it’s still there, less than an inch away from a small electrical arc immersed in heated oil. The steel an inch away becomes too hot to touch, but the part shows no sign of melting. Since it only cost a few bucks to print, we just throw a few spares in the toolkit in case of catastrophic events.

We sell large industrial systems and currently each uses 20 to 30 of the 3D printed parts...in about 7 or 8 different forms.

It’s the Little Things

There are small tricks which make a big difference in the usefulness of 3D printed parts. One of these is Brass Thread Inserts for plastic. These allow a screw to be used to form a strong connection...and they look great too!

Another benefit is text printed right on the parts...other kinds of labels are difficult to apply and become easily destroyed. Printing the label right on the part kills two birds with one filament. The text must be fairly large, at least 0.2” high, but it will never wear out in most use cases. We usually print our name, the part number, and label connectors with a name or number.

After we put some branded parts in the field, one observer noted that we must be getting really big to have custom made plastic parts. Of course he thought we were using injection molding technology, and I did not disabuse him of the notion.

Anyone who tells you that a 3D printer should never be left running unattended has obviously never cranked out a 72 hour print. We have a webcam we can watch to monitor prints remotely and plan to devise a remote power cutoff system so we can shut things down if they go awry.

Conclusion

Buy a 3D printer. If your people can’t make use of it, you need new people.

Photos

Illustration 1: Example 3D Printed Parts

Example 3D Printed Parts Description, clockwise from upper left:

• BNC patch panel with numbering
• printed circuit board hold down bracket
• transducer holder with angle indicator (blue and white)
• working ink marker prototype (also in blue and white)
• fan bracket (also shown installed on the circuit board in the center)
• hold down bracket for installation on an aluminum rod
• bracket for mounting chassis slide rails (still has the skirt attached)

Illustration 2: Print Farm (some of our less fun folks insist on calling it a “garden”)

Illustration 3: the Vuno I

Our biggest single print project is the Vuno I, the black tower in the image above. We needed an enclosure to hold a single board with a power supply underneath, so we printed this in 4 pieces. Altogether, the Vuno required over 130 hours of printing.

If we were to sell this as a product, we would use 3D printing with sanding and painting. This would be a low-volume, higher-cost product where injection molding would be inappropriate and other technologies would be difficult at best.