Are Nylon and Polycarbonate Really Worth It? A Procurement Manager’s Cost Analysis

The Short Answer: It Depends on Your Production Volume and Part Geometry

There's no single answer to whether nylon or polycarbonate is the better buy. I've managed a $180,000 annual budget for custom molded parts at a mid-size manufacturing firm for the past six years, and I've tracked every invoice. What I've learned is that the cost decision shifts entirely depending on your annual volume and the complexity of the part.

Let me break this into three common scenarios I've seen in our procurement system.

Scenario A: High-Volume, Precision-Intensive Parts (10,000+ units/year)

For this scenario, we're talking about replacement gears, bearing cages, or conveyor components—parts where tolerances matter and failure costs are high.

Nylon (specifically, glass-filled nylon 6/6) is typically the more cost-effective choice here. Here's why:

• Raw material cost: Nylon 6/6 resin runs about $2.50–$4.00 per pound (based on Q1 2025 spot prices from major distributors). Polycarbonate is similar—$2.80–$4.50—so the raw spread isn't huge.
• But the real savings come from cycle time. Nylon molds faster in injection molding because it crystallizes more quickly. In one of our 2023 audits, switching from polycarbonate to glass-filled nylon shaved 18% off cycle time, which translated to roughly $0.12 per part savings at high volume.
• Tooling longevity: Nylon is less abrasive to molds than glass-filled polycarbonate. Our mold maintenance costs dropped by about $1,200 annually when we standardized on nylon for these high-volume gear parts.

The catch: Nylon absorbs moisture, which can affect dimensional stability. If your part must maintain tight tolerances in humid environments (think food processing plants), you might need to post-condition or pay for sealed grades, which add $0.08–$0.15 per pound.

"I went back and forth between nylon and polycarbonate for our conveyor chain links for about a month. Nylon offered the cycle time savings, but polycarbonate had better moisture resistance. Ultimately chose nylon with a moisture-sealed grade because the cycle time savings outweighed the material premium by about $4,200 annually at 15,000 units."

Scenario B: High-Volume, Non-Precision Parts (50,000+ units/year, loose tolerances)

This is for things like cable ties, simple clips, spacers, or non-structural housings. Here, the old wisdom says 'go with polypropylene or ABS.' But I think that's outdated advice.

Actually, I've seen a shift in the past two years: recycled polypropylene (rPP) and post-industrial nylon regrind are often cheaper than virgin polycarbonate or nylon. In Q2 2024, we tested a run of 30,000 simple push-fit clips using rPP at $1.20 per pound vs. virgin nylon at $3.10. Total cost savings: $0.09 per unit—or $2,700 total.

But here's what nobody tells you: The real hidden cost isn't the material—it's the reject rate. We had a 2.5% reject rate on the rPP run vs. a 0.3% rate on virgin nylon. That added back roughly $0.03 per unit in scrap. Still net positive, but the margin was thinner than expected.

Scenario C: Low-Volume Custom Parts or Prototypes (Under 1,000 units/year)

This is where polycarbonate often makes sense, despite what the raw cost numbers say.

Polycarbonate is easier to machine and thermoform than nylon. When you're making 50–200 custom parts per year (like replacement panels or custom enclosures), the tooling cost is your biggest ticket item. Polycarbonate sheet can be cut or vac-formed with less expensive tooling than injection-molded nylon. For a run of 200 units, tooling costs might be $2,000 for polycarbonate thermoforming vs. $8,000 for a nylon injection mold.

But—and this is a big but— polycarbonate has lower fatigue resistance and in my experience, scratches more easily. If the part is structural or needs to last 5+ years, nylon might still win on longevity, even with the higher upfront tooling.

"I'm not 100% sure why the industry still defaults to polycarbonate for low-volume prototyping. My best guess is inertia—machinists are just more comfortable with it. But we've been testing compression-molded nylon prototypes for the past two years. The initial cost per unit is higher, but the part survival rate over 3 years is 2x better."

How to Decide Which Scenario You're In

Don't guess. Here's what I do in our procurement workflow:

1. Check your annual quantity. If it's under 1,000, lean polycarbonate for quick tooling. Over 5,000, invest in nylon tooling for longer-term savings.
2. Assess tolerance requirements. ±0.005" or tighter? You probably need glass-filled nylon (or pay for polycarbonate post-machining). Loose fit? rPP is your friend.
3. Think about environment. Constant humidity >60%? Polycarbonate or sealed nylon. Dry indoor use? Standard nylon 6/6 is fine.
4. Run a TCO comparison. I built a simple spreadsheet (happy to share the template) that factors in material cost, cycle time, tooling amortization, scrap rate, and expected part lifespan. Over 5 years, nylon often wins on volume, polycarbonate wins on flexibility.

One last thing: don't take my word as gospel. This is what's worked for our operation—a mid-size manufacturing shop with predictable order patterns. If you're dealing with high-mix, low-volume or extreme temperature environments, your mileage may vary. Take this with a grain of salt and run your own numbers.