Bastiaan Oud and Jonathan Girroir
To the outside eye, injection molding might seem straightforward enough: You shoot hot, liquid plastic into a cavity that is the shape of what you want to build, let it cool, pop it out, and voilà – you have your part.
The reality is a bit more complex. If you build the cavity exactly like the shape you want to pop out of it, you won’t actually get the shape you’re looking for, because as the plastic cools down and solidifies, it shrinks.
It doesn’t shrink uniformly, either: The thermal properties of the part will cause it to warp and twist out of shape in different areas. As a result, in order to get a part that is exactly like you designed it, you have to build the mold in a way that takes shrinkage and warpage issues into account.
Here’s the problem, though: Molds are not exactly cheap to build, so getting to a good solution by trial-and-error can be an expensive undertaking.
The initial mold can cost somewhere in the five-digit to six-digit range to build, depending on its size and complexity. If the manufacturer gets the mold wrong – if parts aren’t coming out right – they have to make physical alterations to the mold, shaving off metal and resizing it until they get better results. These corrections often cost thousands or tens of thousands of dollars – sometimes even hundreds of thousands.
Apart from the cost, there is also the issue of time. In a best case scenario, one of these corrections might take two weeks to implement; more often than not, it can take four to six weeks. If a manufacturer averages even a handful of corrections per mold, it can significantly delay their time to market, and wind up impacting overall profitability.
Time for a virtual approach
Fortunately, injection molders can mitigate these challenges by taking a cue from other manufacturing sectors and embracing virtualization, enabling them to optimize their molds digitally before anything is physically built.
Virtualization allows injection mold manufacturers to simulate the results that they’re going to get from their part, mold and parameters, early in the design stage, when changes can still be made easily.
They can use simulation to find answers to questions like: “What will the resulting end product look like if I build my mold this way, and I build my cooling channels that way, and I adjust the parameters around throughput or temperature in a certain way?” In essence, simulation helps solve the shrinkage and warpage issues by predicting them ahead of time, allowing manufacturers to build their molds more accurately right from the outset.
Avoiding mold errors is no small benefit. For example, a typical large auto manufacturer that produces hundreds of molds every year – each requiring several rounds of corrections – would save a staggering amount of money by using simulation to reduce the number of correction rounds required. The total amount of savings would be in the millions.
But the simulation helps you do more than just avoid errors. It helps you find better solutions. You can find part and mold designs that save cycle time, or reduce the amount of material used, without sacrificing quality. Depending on the size of a customer’s operations, this is often the largest source of value, in the long run.
If this is “the promised land” for injection mold manufacturers, how best to get there?
Change management matters
Certainly, software is part of the equation. Sophisticated simulation software – underpinned by powerful 3D visualization – is what enables users to perform a detailed virtual analysis and optimization, and to clearly understand the impact of every tweak that they make to their design.
But software is only part of the solution. The adoption of virtualization in the injection molding space also requires a change in mindset in order for injection molders to start using visualization and simulation, and to really trust the simulation.
Much of this mindset shift comes down to successful change management. This requires organizations to do a little more “front loading” in the early stages of their design process than they’re historically used to. In other words, rather than racing to create the first prototype, they should involve the downstream people – the ones who do quality control, or who do serial production – early in the design process, to make sure everyone’s aligned. This will cost a bit of time on the front end, but will deliver much greater savings later on.
Of course, it’s always difficult to get people to make a sacrifice early in order to get a delayed benefit – so, it’s critical to paint a very compelling picture of the value of changing old habits and learning a new way of working.
“Start narrow but deep” is good advice here. Aim for a quick win and flagship virtualization success that you can point to. Better to do one virtualization project really well and then have something to talk about than to do five projects in a so-so fashion, where you don’t really have anything impressive to point to. Progress dies when there’s no flagship success serving as a beacon, lighting the way forward.
Tackling the big issues
There couldn’t be a better time for injection molders to get on board with changing their processes, because frankly, there are some pressing issues to address.
Sustainability is probably the most important mega-trend facing the plastics industry, both in terms of consumer perception, as well as regulation that is already in place and will come with added force in the future. Simply put, a manufacturer that doesn’t have sustainability on their strategic agenda is making a big mistake. It should be top of mind for management everywhere.
Once again, virtualization has a role to play here. Not only is it good for the manufacturers – saving them time and money – it’s also good for the environment, because it offers injection molders an opportunity to find out how to reduce plastics waste, through better design.
Virtualization allows injection molders to analyze different trade-offs in their design: If I use this particular material, what will happen? How thin can I afford to make the walls of my part without it becoming fragile, so that I don’t waste material? How can I build the gating system that the liquid plastic flows through, to minimize the amount that solidifies before it enters the cavity and is ejected as waste?
All these things are ultimately engineering design decisions. With virtualization, injection mold manufacturers will have a powerful resource at their disposal to make the best possible engineering and design choices, helping injection molding effectively tackle the various challenges it faces while unmistakably moving the industry forward, into an exciting new era.
About the Author
Dr. Bastiaan Oud is Head of Strategy at SIMCON, and Jonathan Girroir is a Technical Evangelist at Tech Soft 3D.