We were facing a capacity crisis. A new program was coming in, our injection resource planning showed we were running at 90% capacity, and we needed more machines. Fast.

Management had already gotten the quotes: two new 1000-ton high-pressure injection molding machines. The price tag? Around $3 million. Lead time? One year to get the old machines out and the new ones installed.

Meanwhile, sitting in the corner of our shop was a specialized dual-color machine that everyone had written off as useless. It had a unique spigot locking system instead of standard clamps. The one mold designed for it had moved to another molder. We were left with this machine that didn’t match our standardized quick-change back plates. A specialty machine with no purpose, while we scrambled to find $3 million for new capacity.

Here’s what nobody saw: we didn’t have a capacity problem. We had a creativity problem.

That “useless” machine became the equivalent of two fully functional injection presses for $190,000—a fraction of the cost of buying new equipment, completed in 8 weeks instead of a year.

This is a story about hidden capacity. Not the capacity you buy, but the capacity you already own and aren’t using effectively. It’s about machine time as a precious resource that gets wasted not through lack of equipment, but through poor design decisions, inadequate maintenance, and failure to optimize what’s already sitting on your shop floor.

The Machine Everyone Had Written Off

Let me tell you about that dual-color machine.

It had a rotary table designed for color changes, two horizontal barrels for injecting different materials, and that specialized spigot locking system. When the mold it was designed for left our facility, everyone saw the same thing: an incompatible machine we’d need to find just the right customer to utilize.

While we debated what to do with it, we were simultaneously planning to spend $3 million on new machines and remove one of our 300-ton presses. The irony wasn’t lost on me, but the real problem was deeper than anyone realized.

Our planning showed 90% machine utilization. The reality? We were getting 60% run time due to poor maintenance. Worn components, inconsistent cycle times, unplanned downtime that kept eating into our capacity. We weren’t just short on machines—we were bleeding capacity from the machines we already had.

The perfect storm was building.

The Evolution of a Solution

I started asking questions. Not just to engineers, but to everyone who touched our equipment.

I talked to the millwrights about the rotary table. Could it be locked in place? Could we remove the specialized locking system? What was the actual load capacity of that shuttle?

I talked to the process guys about barrel configurations and shot sequencing. What if we disabled the barrel clamps? What if both barrels shot independently instead of sequentially?

I talked to the old injection engineer who’d been around since that machine was installed. What had they originally envisioned? What limitations were real and which ones were just assumptions we’d inherited?

I talked to suppliers about custom modifications and what was actually possible versus what was conventionally done.

One idea led to another. One conversation sparked three more questions. And gradually, a solution emerged that nobody had seen because nobody had asked the right people the right questions.

Here’s what we did:

We removed the locking system from the rotary table and locked the table so it wouldn’t rotate. We conjoined two similar-capacity molds back-to-back on the cavity plates and put the core plates on the stationary and moving platens. Fortunately, all our molds used reverse ejection with hydraulic cylinders on the core side, so I could position cores wherever needed.

We disabled the barrel clamps on both platens and added a bottom plate on the two conjoined molds that mounted to the now-stationary rotary table. The two horizontal barrels could now shoot independently into two different molds.

The moving platen would retract first, then the shuttle carrying the conjoined cavities would move away, and then the robot would come in with a dual-head end-of-arm tool and remove parts from both molds in one cycle. One part on the front of the tooling, one part on the back.

The conversion cost $190,000. We completed it in 8 weeks. We turned one “useless” machine into the equivalent of two fully functional presses.

We didn’t need to buy new machines. We put those additional funds into reducing unplanned downtime instead—addressing the maintenance issues that were really killing our capacity.

The cycle times were amazing. We needed two operators just to keep up with packing the parts.

And if we ever found a money-making opportunity for dual-color molding? Easy to reinstate. In the meantime, we had recovered massive capacity without the year-long wait or the $3 million price tag.

The Resistance Nobody Talks About

Before you think this was a smooth success story, let me tell you about the resistance.

Management had concerns. Maintenance had concerns. Engineering had concerns. Everyone had their special reasons why this wouldn’t work.

Engineering felt the middle shuttle couldn’t carry the load of two large cavity molds—approximately 30,000 pounds combined. They were wrong. The carrying capacity of the shuttle was 60,000 pounds. But nobody had checked because everyone had already decided it wouldn’t work.

The setup guys hated the idea because it required a different system than what they were used to. The stationary platen and shuttle needed clamps instead of our regular quick-change platen. I used the same quick-change system so the molds could easily transfer to other machines if needed, but there was no quick change on this press. The setup crew saw this as a step backward.

I explained that this was intended as a dedicated machine—just like it always had been. We selected long-running programs that were equally compatible for their capacity requirements. The molds only came out for preventive maintenance once per month. The objection wasn’t about function; it was about unfamiliarity.

Maintenance didn’t like the idea of mixing materials, so we made sure we selected jobs that used the same injection material. Just cleaner operations at the press.

Every objection had a solution, but first we had to get past the assumption that because something hadn’t been done before, it couldn’t be done at all.

The hidden capacity was there all along. It was revealed by engaging all stakeholders, listening to feedback, and being willing to think beyond “the way we’ve always done it.”

The Principle: Machine Time Is Your Most Expensive Resource

That dual-injection conversion taught me something fundamental about manufacturing: machine time is often your most constrained and expensive resource, yet it’s the one companies waste most casually.

Not through obvious negligence, but through dozens of small design decisions and maintenance compromises that add up to massive capacity loss.

Let me show you what I mean.

The Insert Change That Cost 23 Days Per Year

Remember that defroster grille project I mentioned in a previous article—the one that cost $800,000 to rebuild? That failed mold had another problem beyond warpage and mounting failures.

The insert change system required pulling the mold from the press. Eight hours of downtime. A full shift, every single time we needed to change inserts.

We were changing inserts one to two times per week. Let’s say 1.5 times per week on average.

Do the math: 7 hours recovered per change × 1.5 changes per week × 52 weeks = 546 hours per year.

That’s nearly 23 full days of production time lost to a bad insert design.

When we built the $800,000 replacement mold, I specified a front-load insert change system. The tool maker on the original $327,000 mold had told me it wasn’t possible. I knew better—I’d done it before on other programs.

The new system allowed insert changes in one hour. In the press. No mold removal required.

We absorbed the cost of that design improvement in the $800,000 rebuild. But the capacity recovery? That was 546 hours per year we got back. Twenty-three full production days that had been disappearing into unnecessary downtime because of a design decision someone made—or didn’t make—during the original mold build.

The Horn Pins That Stole 12 Days Per Year

Here’s another common capacity killer: poorly designed horn pins that break regularly.

How often do horn pins break? It depends on operator awareness and setup practices, but I’ve seen averages of one break per month over a year in shops that don’t address the root cause.

When a horn pin breaks, you don’t just fix it. You pull the mold from the press, make the repair, reset everything, and get back to producing quality parts. That’s typically three shifts—24 hours of downtime.

One break per month × 24 hours = 288 hours per year. Twelve full production days lost to something completely preventable.

Front-load horn pin designs eliminate most of these failures. The design change costs money upfront during mold build, but it pays back immediately in recovered capacity and eliminated unplanned downtime.

Unplanned downtime shouldn’t exist in your schedule. When it does exist, it’s usually because someone made a design decision—or failed to make one—that prioritized initial cost over operational efficiency.

The Part Layout Nobody Optimized

Here’s a more subtle form of wasted capacity: poor part layout in mold design that forces you to use a larger press than necessary.

I’ve seen molds with unnecessarily high stack heights that require bigger machines. I’ve seen molds with weight distributions that demand more tonnage than the part actually needs. With more thoughtful design, these molds could run on smaller, more efficient machines.

The challenge is that part design typically drives these constraints. The geometry of the part limits what you can do with orientation and layout in the injection process. You’re somewhat restricted by what the part itself demands.

But here’s the critical insight: the real place to start for optimization of injection process machine utilization is at the part design stage. Always.

When you’re designing the part—before you’ve committed to geometry, before you’ve finalized wall thicknesses, before you’ve determined gating locations—that’s when you have the freedom to make decisions that optimize machine utilization.

Once the part design is locked, you’re managing constraints. But during part design, you’re creating possibilities.

It always makes sense to optimize cavity position and orientation for clamp tonnage and die pull requirements. But if the part itself is designed without consideration for how it will be molded, you’re starting with one hand tied behind your back.

This is why I’m so adamant about front-loading the design process. The decisions you make—or don’t make—during part design create ripple effects that either optimize or waste your machine capacity for the entire life of that program.

A part designed with moldability in mind might run efficiently on a 300-ton press. That same part, designed without considering injection molding requirements, might need a 500-ton press and still have chronic quality issues.

The cost difference isn’t just the machine size. It’s cycle time, it’s energy consumption, it’s the opportunity cost of tying up your larger press when it should be running programs that actually require that capacity.

The Maintenance Reality Nobody Wants to Face

Let’s go back to that capacity crisis I mentioned at the beginning. We planned for 90% machine utilization. We were getting 60%.

The 30% gap wasn’t because our planning was wrong. It was because our machines weren’t performing the way they should.

Worn back pumps. Leaky seals. Deteriorated slip rings. Components that were slowly degrading, causing the machines to run at elongated cycle times or produce scrap parts due to fluctuating shot sizes.

It looked like we needed more machines. What we actually needed was to maintain the machines we already had.

Here’s the tendency I see everywhere: companies perceive routine maintenance as not being directly related to profit, so it gets deferred. The maintenance budget gets cut when times are tight. Preventive maintenance schedules slip because there’s always a hot job that needs to run.

But routine maintenance is directly related to profit. Regular, systematic maintenance that keeps your machines performing the same as when they left the factory is key to maintaining good cycle times, optimum efficiencies, and limited unplanned downtime.

Downtime is manageable when it’s planned. Unplanned downtime is a cancer that eats your capacity, your schedules, your customer relationships, and ultimately your profitability.

When a machine isn’t properly maintained:

• Cycle times elongate (lost parts per day)
• Shot sizes vary (increased scrap rate)
• Clamp force decreases (quality issues, larger safety margins)
• Response times slow (longer cycles, reduced output)

None of these failures are dramatic. They’re incremental. You don’t suddenly lose 30% capacity—you lose 1% here, 2% there, 3% somewhere else. Over time, across multiple machines, it adds up to running at 60% of your planned capacity.

Then you look around and say, “We need more machines.”

No. You need to maintain the machines you have.

I’ve never seen a scenario where longer cycle times equal more profit. What I’ve seen repeatedly is broken machines running at elongated cycles because the clamp isn’t strong enough due to failing back pumps or leaky seals. I’ve seen scrap rates climb because slip rings are worn and nobody wants to spend the money to replace them.

The parts that fail are rarely catastrophic on their own. But their cumulative effect is devastating to your capacity utilization.

The Pattern: Hidden Capacity Lives in Design Decisions

Let me tie all of these examples together.

The dual-injection conversion that saved $2.8 million wasn’t about buying new equipment. It was about seeing possibilities in equipment everyone else had written off.

The 546 hours per year lost to insert changes wasn’t about the mold being old. It was about a design decision during the original build—a decision to not include front-load insert capability because the tool maker said it wasn’t possible (even though it was).

The 288 hours per year lost to broken horn pins wasn’t about operator error. It was about a design decision to not include front-load horn pins because they cost more upfront.

The molds running on oversized presses aren’t about bad luck. They’re about part designs created without consideration for injection molding optimization.

The 30% capacity gap between planned and actual utilization wasn’t about having too few machines. It was about maintenance decisions—or lack of decisions—that let machines slowly degrade below their design performance.

Every single one of these capacity losses traces back to a design or maintenance decision where someone chose the cheaper or faster option upfront, not realizing they were creating ongoing capacity waste that would cost far more over time.

This is why I’m so persistent about front-loading the design process and implementing systematic maintenance practices. The decisions you make during design—about part geometry, mold features, insert systems, horn pins, cavity layout—determine your machine capacity utilization for the entire life of the program.

The machine time you waste or recover doesn’t happen on the shop floor during production. It happens in the design office, during part design and mold design, when you’re making decisions about how things will be built and maintained.

What This Means for Your Shop Right Now

If you’re facing capacity constraints—if you’re planning to buy new equipment, if you’re turning down work because you don’t have available machine time, if you’re constantly firefighting to meet production schedules—stop and ask yourself these questions:

What specialized or underutilized equipment do you already own?

Is there a machine sitting idle or running part-time because “it doesn’t fit our standard system”? What would it take to adapt it? What creative solution haven’t you explored because everyone assumes it won’t work?

We almost spent $3 million on new machines while a perfectly good machine sat in the corner because it had a different clamping system. The “useless” machine became our most valuable asset once we were willing to think differently about it.

Where are you losing hours to insert changes, maintenance interventions, or design features that waste time?

Walk your shop floor. Talk to your setup people and operators. Where do molds come out of presses regularly for things that could be done in-press with better design? Where are molds coming out for repairs that shouldn’t be necessary with proper preventive design features?

Every hour of downtime per week multiplies by 52. Seven hours per week is 364 hours per year—more than 15 full production days. What’s that capacity worth to you?

What’s your actual machine utilization versus your planned utilization?

Don’t just look at schedule loading. Look at actual performance. Are your machines running the cycle times they should? Are you seeing scrap rates that indicate inconsistent shot sizes or process variation? Are you experiencing unplanned downtime that shouldn’t exist?

That gap between planned and actual utilization is hidden capacity. It’s not on a machine you need to buy—it’s on the machines you already own that aren’t performing the way they should.

Are your part designs optimized for machine utilization?

This is the hardest question because it requires going back to the beginning. But it’s also the most important one.

When you’re designing new parts, are you considering moldability from the start? Are you involving manufacturing and tooling experts early enough that they can influence part geometry decisions? Are you making trade-offs between part design preferences and manufacturing efficiency?

Or are you finalizing part designs first and then asking manufacturing to “figure out how to make it”?

The real place to start for optimization of injection process machine utilization is at the part design stage. Always. Once the part is designed without consideration for manufacturing efficiency, you’re managing constraints for the life of that program.

Are your maintenance systems preventing problems or just reacting to failures?

Unplanned downtime shouldn’t exist. If it does, you don’t have a maintenance problem—you have a maintenance system problem.

Systematic preventive maintenance, consistent execution of best practices, capturing and applying lessons learned—these aren’t luxuries when times are good. They’re the foundation that keeps your planned capacity from eroding into actual capacity losses.

The Lesson I Keep Learning

I’ve been doing this work for 35 years. I’ve managed launches at GM and Stellantis. I’ve troubleshot hundreds of molds and optimized dozens of manufacturing operations. And the pattern I keep seeing is this:

Companies are surrounded by hidden capacity they can’t see because they’re not asking the right questions or listening to the right people.

That dual-injection conversion happened because I talked to millwrights, process engineers, old-timers, and suppliers. The solution emerged from combining their knowledge in ways none of them had considered individually.

The insert change optimization happened because I knew front-load systems were possible, even when the tool maker said they weren’t. The knowledge existed—it just needed someone willing to push back on “we can’t do that.”

The horn pin failures stopped when we implemented front-load designs. The solution existed in the industry for decades—it just needed someone willing to spend the money upfront to prevent the ongoing capacity losses.

The capacity gap closed when we stopped deferring maintenance and started treating machine performance as a critical resource. The knowledge of what needed to be done existed in our maintenance team—they just needed leadership support to actually do it systematically.

The hidden capacity is already sitting in your shop. It’s in the machine everyone has written off as specialized or incompatible. It’s in the design decisions you haven’t questioned because “that’s how we’ve always done it.” It’s in the maintenance you’re deferring because it doesn’t feel directly connected to profit. It’s in the stakeholder knowledge you’re not accessing because you’re not asking the right questions.

You don’t need more machines. You need to optimize the capacity you already have.

Getting Started: Three Actions You Can Take This Week

1. Walk your shop floor with fresh eyes.

Look for machines that are underutilized, specialized, or sitting idle. Ask yourself: “What would it take to make this machine productive?” Don’t accept “it’s incompatible” as a final answer. Ask the people who actually work with the equipment—millwrights, setup technicians, experienced operators—what they think is possible.

2. Calculate the hidden costs in your current molds.

Pick three high-volume molds. How often do they come out for insert changes? For maintenance? For repairs? How long does each intervention take? Multiply those hours by your run frequency and calculate the annual capacity loss. Now imagine recovering 80% of that time through better mold design. What’s that capacity worth?

3. Review your maintenance systems honestly.

What’s your planned machine utilization versus your actual performance? Where’s the gap? Is it because you need more machines, or because your existing machines aren’t performing as designed? Talk to your maintenance team. Ask them what’s being deferred, what’s failing predictably, and what would improve if you invested in systematic preventive maintenance.

The answers to these questions might change your entire capital planning strategy. Before you spend millions on new equipment, make sure you’re using the capacity you already own.

Facing capacity constraints and considering new equipment purchases? Launchpad Project Management helps manufacturers uncover hidden capacity through design optimization, systematic maintenance implementation, and creative problem-solving. Sometimes the machine you need is already sitting in your shop—you just need someone who knows how to see it. [Let’s talk about optimizing the capacity you already have.](contact page link)