Over the years I have used a variety of machines to make round cores and core pins, but the Ded-Tru is probably the best inexpensive toolroom precision grinder.  I am sure there are high end CNC grinders available that can do the job faster and maybe better, but, for the money, the Ded-Tru is a great machine.

Not that I like running it, in fact, I really don’t!  However, you gotta do what you gotta do to get the job done, right? The reason I don’t really like using it is because you have to just stand there and do the same procedure over and over again, without ever varying the method.

On the other hand, this grinder can do some very impressive work. It also requires a high degree of skill and patience in order to be used efficiently. Not just anybody can walk up to it and figure out the proper set-up procedures; as well as the endless subtleties of form grinding and concentricity.

If you have ever ground hardened tool steel on an automatic surface grinder that uses flood coolant, you probably have noticed that the coolant cools the workpiece to a much lower temperature than the ambient air temperature in the room. This means the workpiece has contracted in size, while your height gage or gage blocks have not.

So, you might think your block is exactly the correct size, but the next day you discover that it has mysteriously grown in size. The bigger the block, the more the size changes.

In the past, I guessed from experience how much change would occur, and this worked OK. But then came some mold cavity blocks made out of D-2 tool steel. Anyway you machine this tough stuff, it is a problem. In fact, maybe it should be illegal!

What I started doing with great success, was keeping gage blocks set up next to the workpiece while it was being ground. Obviously, you can’t have the correct amount because you would be grinding them when you got to size. You could always set them far enough away from the grinding, but I think it makes more sense to keep it close for the sake of accuracy.

You then use a very small granite surface plate and your height gage with a dial indicator to physically inspect the height of the workpiece. Keep everything clean, use good practice and you will find this method works very well.

You might also use a magnetic base on the wheel guard with an indicator, but I find the vibration of the machine disturbs my measurement.

Crazy Mike

During my years as a plastic injection mold maker I have encountered some very strange individuals. Now, they might say the same about me, but these guys were truly over the top.

My favorite case is a man named Mike. I was working in Seattle, and the mold making shop was typical of those in the area because it had so many people from all over the world. In fact, I think we had at least 10 nationalities represented there. Mold makers from Taiwan, Korea, Germany, Portugal, Hungary, Switzerland, Poland, Brazil and various other countries.

Mike, however, was born and raised in the Denver area. He was a Viet-Nam vet and was clearly affected by the horrors of war. He used to randomly laugh like Satan, quite loudly so that anyone in the building could hear. Then he would begin talking about burning gooks and laugh again.

I tried to befriend him, thinking I might be able to help him in some way. I even had him come to church with me once. Unfortunately, he scared the little children and the parents asked my why I brought him there. They were right, I should have just met with him one-on-one, if at all.

The last day I saw him at work, before he took off to rescue his daughter, was when I gave him a ride one Saturday morning to go to work. When we arrived at his apartment, we found him sitting in an overstuffed chair, surrounded by 24 oz. bottles of malt liquor and breathing in huge quantities of marijuana smoke that filled the room.

Somehow he managed to get to work with us, the next day he was gone.

Two months later he returned from rescuing his daughter in Denver. Seems she had some rough times and so did Mike. He came into the shop with no shirt on, broken glasses, and a gun in his pants waist!

He was ranting how he was the best mold maker in the shop and demanded his job back. I don’t know how the very civilized Swiss owner managed it, but Mike disappeared, never to return. Thankfully!

Tell us your story, just leave a comment.

Have you ever had an awesome boss while working in anything related to plastic injection molding? Since I have been in this business, which goes back to 1978, I have had quite a few good and some less than good bosses.

One excellent boss I had in a plastic injection molding company was from Switzerland  and his name was Karl. Every day he was immaculately dressed and on top of everything that went on in every aspect of the company. It took me  a long time to get hired and I knew I was in for a real experience, but I wanted to learn my trade from the best.

The very first day I was standing with the foreman looking over some prints. There was no heat on because it was early spring, so the shop was pretty cool. I had my cold hands in my shopcoat pockets when Karl spied me. He marched right over, yanked my hands out from my pockets, and proceeded to slap them, telling me to “never put your hands in your pockets!”

I should have known better, having lived in Northern Europe for a few years, but, hey, it was cold! In the end, we became good friends and I did learn a great deal of craftsmanship from this old school master.

One of the nicest I had was an elderly man who had the unfortunate bad habit of smoking and drinking coffe all the time. This was back before the days of no smoking in the shop, so his fingers were actually yellow from the smoke. What made him nice was that he was so patient with us apprentices, but what made him almost intolerable was his breath!

He used to come up to each of us every morning to greet us and give us an assignment or check on our work. That is when his kindness became his curse. Because he was only inches away from our face we just had to eventually breathe in his absolutely horrible stench of a breath! More than one guy actually gagged and nearly vomited!

Another boss I had was a Russian who grew up in the German part of Brazil.  He could speak so many languages and seemed to know a million people. He was great because he took time to explain things without making any of us beginners feel like idiots.

What about you, do you have any stories of a good or bad boss in your plastic injection molding or mold making career?

There is a new website out there called www.BestMoldDesign.com, which is about  mold design for plastic injection molds. Some pages discuss how to design gates, how to design runners, how to vent a mold, tips for general injection mould design and much more.

Stack up for a mold design

Mold design

You can find out how to find and pick a mold design company, learn about hot tip mold design and find out where to buy the best injection mold design tutorial anywhere.

Mold design is a highly skilled, specialized profession that is in big demand. Despite the fact that many companies have chosen to outsource their work, many designers are very busy working on high-end proprietary projects.

How to choose a mold design company

The plastic injection molding future is looking quite bright for those companies who have survived all the turmoil of the past decade or so. The number of companies who have gone out of business is staggering, yet, for those who remain, the business just keeps on growing.

Even with the huge flow of work going to cheap labor countries more and more products are designed that need plastic molding.

www.BestMoldDesign.com

Very often, when somebody is trying to understand how the plastic injection molding process works, they are referred to a detailed explanation of the mechanics of an injection mold and molding machine. This is an interesting and fascinating topic, to be sure, but there is another aspect to this process that needs to be addressed.

Most people probably never really consider just how all the plastic products they use each and every day are manufactured. This is understandable, because few people have had an insider’s look at a mold making or molding facility.

Just consider for a moment how many professions are involved in creating a cell phone, for example. First, somebody had to come up with the idea, then he had to find somebody to analyze the feasibility of pursuing the idea.

Marketing experts, industrial designers, artists, prototype mold makers, plastics engineers, molding technicians, injection mold makers, mold designers and process engineers are just some of the professionals that could be involved.

This does not include the electrical engineers, all the countless people involved in the electronic functions, the apps engineers, the commercial artists, and the quality engineers required to bring such a commonplace item to market.

On top of this, consider for a moment that this is done on a global scale. Parts are made anywhere these days, designs can be done in India and sent electronically to California, the mold built in the Czech Republic, molding done in Romania, and the marketing done in New Jersey.

You can read more about the plastic injection molding process at http://global-plastic-injection-molding.com

The business of plastic injection molding is mostly scientific and technical, yet there is this element of undefined experience that can only be termed “black art”.  Mold polishing seems to fall into this category for many engineers and mold techs.

If the part has blemishes of one sort or another, or is sticking in the cavities, or maybe not filling properly, very often the solution is related to the surface finish.

This is often overlooked, which is unfortunate because it is much less costly than a major engineering change, for example. When the process has been tweaked over and over again, maybe take a second or third look at the mold polish, it could hold the answer.

Learn more about plastic injection molding and mold polishing.

A small, but very effective tip for easier plastic injection molding set up is to standardize the clamping slots on the top and bottom plates of all mold bases. This little trick might seem obvious, but it is surprising how many custom molders have every size imaginable in their mold base inventory.

With this method you need only one size clamp, which can be custom made or likely purchased. The set up techs won’t need to be fumbling about for the right size clamp, there will be no shims under clamps and you can be sure the molds are held in place securely.

This is also a good idea from the standpoint of training. There is enough to learn without adding another item to the list of how to set up a plastic injection mold. Once this is in place, it will quickly become a SOP, standard operating procedure.

All your future designs must have this incorporated, which, for some reason, is not as easy as it might seem. You likely will still have the occasional mold that comes in the wrong size, but in time they will all be standardized.

Learn more about plastic injection molding and injection mold making.

Lately I have noticed a trend in which companies gradually reduce their plastic injection molding machine supplier base to just one company. This makes a lot of sense, in many ways, yet it also is limiting in other ways.

Sure you can get great discounts by buying several machines from the same supplier, such as Engel,  but once you get more or less into a mono-culture, you miss out on the innovations of other companies.

This presents somewhat of a dilemma for companies however. Perhaps one way to deal with this issue is to have various brands on the floor, each specializing in the things they do best. Hydraulic vs. electric, rotary presses, vertical, or stack molding presses are some examples.

Learn more about the injection moulding of plastic parts.

Remember when your plastic injection mold delivery date was 2 or 3 months out? And the molding product date was even further out? My how things have changed!

These days about the only way to get good molding work is to promise a very short delivery date and then actually deliver.  On top of that, the quality and price must be extreme as well.

This requires the best of almost everything, all at the same time. 5 axis machining, hard milling, CNC EDM with robotics, WEDM’s running 24/7, a flawless mold design, great surface finishes done with little polishing, and so on. Presto! There you go, you are in the dough!

Randy Hough writes about plastic injection molding.