Cost-Effective Solutions for Battery Case Moulds: Tips and Tricks

we are going to be honest. Your screen has a feeling of taunting you with a bettery case mould project plan.

The schedules are aggressive, the market need of new battery powered everything is off the charts and that line item of tooling? It is looking at you, a large, brash figure which causes the finance department to sweat. In the electronic, or automotive industry, the battery case mould is a colossal component of the budget to any Supply Chain Director or Project Manager. It is a bulky, costly and very essential part of the puzzle.

We can be too much into a rut. We accept the playbook of the old business rules and make a purchase order of the new mould at a quoted price as a fixed cost of doing business. But what in case it is not? What would you say to a way of cutting that cost by a large margin, and with no increase at all in the amount of risk on your project, and without compromising on quality?

This is not to do with locating some magical, cheap supplier who is promising the world at half the price. And we have all been burned on that story. This is a matter of being smarter. It is a how to guide on re-thinking your approach to mould procurement stuffed with efficiency strategies and production tips that get you back in control of the budget.

Ok, So, Where Do We Start?

The greatest fallacy that most teams commit is to consider cost only after their quotes are received back. At that point, it is too late. Cost-saving decisions that are most effective are made far in advance of the first chip of steel being cut. The design is the beginning.

I know, I know. It is like trying to turn a battleship with a canoe paddle in order to get engineering to alter a design. However, the thing is that a minor change in CAD file can be converted into tens of thousands of savings on the mould. And this is where the very idea of Design for Manufacturability or DFM will become your best friend ever. It is a fancy name of a simple concept: make the part easy to make.

Consider it in this light: you would not allow an architect to design a house without speaking to the construction crew at all, would you? You would hope that the builder would examine the blueprints and tell you, “You know, that wall could be shifted six inches and we could use standard lumber sizes and save a fortune.” It is the same principle. You must involve your mould maker early and I mean early. Show them the part design when it is not solid yet. They will see the features that are going to give them headaches and cost twice what they should–the heavy ribs, the undercuts that are not needed, the impossible tolerances. An excellent mould maker is a business partner, not a supplier. This is gold in the form of their feedback.

There is also the steel. It is a default thinking in many firms. Oh, that is a battery case, we want P20 steel. But do you? Do you? P20 is an excellent, all-purpose tool steel, there is no doubt. However, that is not the only solution. When you are only making 250,000 pieces rather than 2 million, would you be able to use a high quality aluminum tool or some other kind of steel that is cheaper? Conversely, when this component will be running year after year, perhaps it would make better financial sense to invest in a more robust steel with higher wear resistance such as H13 or stainless S136 since it will last longer and therefore less maintenance. It is the classic trade off between life in the mould and front loading the budget but it is a discussion you need to be having. Don t be a default. Question it.

Let Us Discover Savings That are in Plain Sight

All right, then you have the design team and the mould maker communicating. That is a massive victory. It is time now to come to the nitty gritty of the mould design itself. This is whereby a few easy decisions can make a colossal difference in the end price tag.

And first of all: standardization. Your mould maker is not smiting the whole mould in one piece out of a block of steel as did some old-fashioned blacksmith. They are putting it together out of hundreds of parts. And what do you know? A great deal of such components are available on shelves. Consider those mould bases, ejector pins, leader pins, bushings, even hot runner systems. There are whole businesses such as DME and Hasco that have been established on supplying these standard components.

So what? Since a custom-machined part will always be more costly than a standard one. Always. When you ask your mould maker to make use of standard parts as much as is feasible, you are not only saving money on the initial build. You are also sparing yourself the infinite headaches later in life. What happens when an ejector pin breaks in the middle of a production run, would you like to wait three weeks to have a custom one machined or do you want to order a standard one that comes tomorrow? No brainers.

Now it is time to discuss simplicity. Any complexity that you put in a part costs you money in the mould. These include the largest culprits which are things that do not allow the part to eject cleanly out of the mould in a straight line. We mean things such as side holes, snaps or clips, and these usually need what the mould people call actions, such as slides and lifters. These are dynamic components in the mould which must move and retract in a flawlessly choreographed step each and every cycle. They are superb examples of engineering, but they are costly to construct, difficult to service and a frequent source of collapse.

This is another opportunity to have a cordial discussion with your design engineers. Ask, is this undercut absolutely necessary? In some cases the answer is yes. More often than not, however, it is possible to dispense with a slide altogether, by a touch of design–a different snap feature, a different opening position. The one change would save 10-20 percent on mould cost and eliminate a huge maintenance liability.

And goodness gracious, use the software! Mould flow analysis software such as Moldflow by Autodesk is the final measure twice, cut once tool of injection moulding. It is a computer simulation which forecasts the flow of the plastic into the mould, its cooling and warping. It will show you possible trouble areas such as air traps, weld line or notorious non-fill areas before you have wasted a dime on steel. Yes, it does cost a bit of money to do the simulation. And that is nothing–and I mean nothing–to the expense of having to draw a multi-ton mould out of a press to repair a defect that might have been foreseen. Tool change and the lost production are astronomical. The least expensive insurance policy that you will ever purchase is a flow analysis.

It is Not Just a Lump of Steel, It is a Joint Venture

All this advice can be followed but in the event that you select the wrong mould-making partner then it can all go awry. We have all experienced it, you get three quotes and one is radically cheaper than the others. Isn t that tempting? However, as every experience project manager would know, the lowest bid is usually the most costly in the long term.

Cutting steel is not all that a good mould maker is involved in. They communicate. They provide solutions. They put intelligent questions and criticize your assumptions. During the vetting process of suppliers, do not only consider the price. Enquire how they do it. Request some examples of DFM feedback that they have provided to other clients. Paying a little more to a store that will spare you of a massive design flaw is an unbelievable offer.

This raises the unavoidable domestic-versus-overseas sourcing discussion. This is not a simple question to answer, and frankly speaking, it is not a geographical issue but more of a communication and trust issue. The savings of sending overseas can be large but you must include shipping charges, possible tariffs, communication issues and time delays to do revisions. In some cases, the time and teamwork aspects of using a local shop may well be worth the extra cost up front. It is up to you to crunch the numbers of your particular project.

And cycle time, please! The price of the mould is a capital outlay. The operation of that mould is a recurrent operating cost. I will tell you how. Suppose there are two quotations. Mould A is priced at 80 000 and its cycle time is 30 sec. Mould B is more expensive ($90,000) and has a cycle time of 24 seconds but is cooled better and the mechanics are more efficient.

That is a huge difference of six seconds. Mould B will complete the job almost 833 hours earlier over a run of 500,000 parts. That is over a month of machine time, paying your operator and electricity that you saved. It is like suddenly that extra 10,000 dollars with Mould B looks like one of the brightest investments you ever had. Now as a project manager or supply chain director this is your opportunity to rise to the occasion by concentrating on the Total Cost of Ownership rather than the purchase price.

The little things that mean a lot.

And lastly, a few little trade secrets which can save you real money. This is the information that is usually missed out when there is a hurry to initiate a project.

First, have realistic expectations in regard to surface finish. It is an extremely time-consuming process to polish a mould to a mirror finish. It requires the labor of a skilled technician whose labor takes hours and hours. Now question yourself: does all of your battery case require that? The superficial cosmetic layers, yes. And the inside, invisible surfaces? Probably not. It can be a lot of money to specify a standard machine finish (such as an SPI-C1) on non-cosmetic surfaces. In your drawings be specific and only specify finishes where it is functionally or aesthetically critical.

Second, prototype smartly. Spend a few hundred or a few thousand dollars on a prototype before you give the final green light on a six figure steel mould. This is easier than ever with today technology. It is possible to order a high-fidelity 3D print to test the fit and ergonomics. A bit extra will buy you a soft tool, of aluminum. You may only get a couple of hundred parts out of this tool, but you will have actual injection-moulded samples to test. You could check the fit, the functionality, the snap features, all of it. It is a small inconvenience to find a design flaw at this stage. Its discovery after the hard tool is manufactured is a disaster.

Ultimately, the idea behind cost-effective manufacturing of something as complicated as a battery case mould is not to be cheap. It is not a question of getting all the pennies out of your suppliers. It is a matter of being intentional. It is about putting in the up-front effort, creating a partnership between your design team and your manufacturing partners and thinking about the lifecycle of the product not just the first purchase order.

With a little bit of smart design, strategic decisions regarding the selection of materials and components, and solid relationships with suppliers, you can take complete control of your tooling budget. You have the ability to provide a quality part, on time and make that number on the spreadsheet one that you can be proud of. You can do this.