Delrin Material Weight Calculator
Calculate precise weights and costs for Delrin (Acetal) rods, sheets, and tubes.
Based on Delrin (POM) density of approx. 1.42 g/cm³.
Material Weight Comparison (Same Volume)
Compares your specific geometry against other common engineering materials.
What is a Delrin Material Weight Calculator?
A delrin material weight calculator is a specialized engineering tool designed to estimate the mass of Acetal (Polyoxymethylene or POM) components before manufacturing. Delrin®, a brand name commonly used for Acetal Homopolymer, is a thermoplastic known for its high stiffness, low friction, and excellent dimensional stability.
Engineers, machinists, and supply chain managers use this calculator to determine shipping weights, material costs, and structural loads. Because plastics vary significantly in density—with Delrin being roughly 40% heavier than water—accurate calculation is crucial for logistics planning and cost estimation in CNC machining and injection molding projects.
Unlike generic calculators, this tool specifically utilizes the density profile of acetal resins (approximately 1.41–1.42 g/cm³), ensuring that your estimates for rods, sheets, and tubes are precise enough for professional quoting and inventory management.
Delrin Material Weight Formula
The core logic behind the delrin material weight calculator is derived from the fundamental physical relationship between mass, density, and volume. The formula is:
Mass (W) = Volume (V) × Density (ρ)
Where the Density of Delrin is taken as 1.42 g/cm³ (or 0.0513 lbs/in³). The volume calculation depends on the shape of the stock material:
| Shape | Volume Formula (V) | Variables |
|---|---|---|
| Round Rod | π × r² × L | r = radius, L = length |
| Rectangular Plate | L × W × T | L = length, W = width, T = thickness |
| Tube | π × (R² – r²) × L | R = outer radius, r = inner radius, L = length |
Variable Reference Table
| Variable | Meaning | Typical Unit | Typical Range (Delrin) |
|---|---|---|---|
| ρ (Rho) | Material Density | g/cm³ | 1.41 – 1.42 |
| L | Length | mm / m | 10mm – 3000mm |
| Ø | Diameter | mm | 3mm – 250mm |
Practical Examples
Example 1: CNC Lathe Stock
A machinist needs to order material for a turning job. They require 100 pieces of Delrin rod.
- Input Shape: Round Rod
- Diameter: 50 mm
- Length: 200 mm per piece
- Quantity: 100
Calculation:
Radius = 2.5 cm. Length = 20 cm.
Volume = π × 2.5² × 20 ≈ 392.7 cm³.
Weight per piece = 392.7 cm³ × 1.42 g/cm³ ≈ 557.6 grams (0.56 kg).
Total Order Weight: 56 kg.
Example 2: Fixture Base Plate
An automation engineer is designing a low-friction base plate.
- Input Shape: Rectangular Sheet
- Length: 500 mm
- Width: 300 mm
- Thickness: 20 mm
Calculation:
Volume = 50 × 30 × 2 = 3000 cm³.
Weight = 3000 × 1.42 = 4260 grams.
Result: 4.26 kg per plate.
How to Use This Delrin Material Weight Calculator
- Select Geometry: Choose Rod, Sheet, or Tube from the dropdown menu. This changes the input fields to match your stock type.
- Enter Dimensions: Input values in millimeters (mm). Ensure all fields are filled. For tubes, the inner diameter must be smaller than the outer diameter.
- Set Quantity: If you are calculating a batch order, increase the quantity field.
- Input Cost (Optional): To get a financial estimate, enter the current market price per kilogram of Delrin.
- Review Results: The tool updates instantly. Use the "Copy Results" button to paste the data into your purchase order or engineering notes.
Key Factors That Affect Delrin Weight Results
When using a delrin material weight calculator, consider these real-world engineering factors that can influence the final figures:
1. Density Variations (Homopolymer vs. Copolymer)
While standard Delrin (Homopolymer) has a density of ~1.42 g/cm³, Acetal Copolymer (often sold as Celcon®) has a slightly lower density of ~1.41 g/cm³. While small, this 1% difference adds up in multi-ton orders.
2. Manufacturing Tolerances
Extruded plastic stock is rarely exactly the nominal dimension. A "50mm" rod is typically extruded slightly oversized (e.g., 50.5mm) to allow for machining finishing. This "plus tolerance" means the actual bar you receive will be heavier than the theoretical calculation.
3. Moisture Absorption
Unlike Nylon, which can absorb up to 7-8% water by weight, Delrin has very low moisture absorption (~0.2%). This means the calculated weight is highly stable regardless of humidity, making financial planning more accurate than with polyamides.
4. Thermal Expansion
Plastics have high coefficients of thermal expansion. If you measure a large Delrin sheet in a hot warehouse (35°C), it will have a larger volume than in a cool lab (20°C). While mass is constant, dimensional checks against weight might vary slightly with temperature.
5. Saw Cut Kerf
If you are calculating the weight of raw stock needed to produce 100 parts of 100mm length, remember to account for the blade width (kerf) lost during cutting (typically 3-5mm per cut). You will need to buy more total length (and thus weight) than the pure sum of the parts.
6. Void Content
Ideally, Delrin stock is solid. However, centerline porosity is a known issue in large diameter Acetal rods. Significant porosity can slightly reduce the effective density of the bulk material, though for billing purposes, you still pay for the volume.
Frequently Asked Questions (FAQ)
Is Delrin heavier than Nylon?
Yes. Delrin (Acetal) has a density of ~1.42 g/cm³, while Nylon 6/6 is approximately 1.15 g/cm³. A part made from Delrin will be roughly 23% heavier than the identical part made from Nylon.
Is Delrin lighter than Aluminum?
Yes, significantly. Aluminum (6061) has a density of ~2.70 g/cm³. Delrin is almost exactly half the weight of Aluminum, making it an excellent lightweight replacement for metal gears and bushings.
Does color affect the weight of Delrin?
Generally, no. Whether you use Black Delrin or Natural (White) Delrin, the density remains consistent. The pigment percentage is negligible regarding total mass.
Why do I need a specific Delrin calculator?
Using a generic "plastic" weight calculator often defaults to a density of 1.0 (water) or an average like 1.2. Since Delrin is dense (1.42), generic calculators can underestimate shipping weight and material cost by nearly 30%.
What is the weight of a 4×8 ft sheet of Delrin?
A standard 4×8 foot sheet (approx 1220mm x 2440mm) at 1/2 inch (12.7mm) thickness would weigh roughly 54 kg (119 lbs). Always verify thickness tolerances with your supplier.
Can I calculate the cost of my machined part with this?
This calculator estimates the material cost of the raw stock. It does not account for machining time, labor, tooling, or machine depreciation, which usually make up the bulk of the final part cost.
Does this calculator work for PTFE or UHMW?
No. PTFE is much denser (~2.2 g/cm³) and UHMW is lighter (~0.94 g/cm³). Using this delrin material weight calculator for those materials will result in significant errors.
What is the scrap value of Delrin?
Delrin scraps are recyclable but generally have lower resale value than metal chips. While you pay for the full weight of the stock, the material removed during machining is usually considered a sunk cost.
Related Tools and Internal Resources
Explore our suite of engineering and financial estimation tools to streamline your production workflow:
- Aluminum Weight Calculator – Calculate weight for 6061 and 7075 alloys.
- Nylon vs. Delrin Cost Comparison – A financial breakdown of choosing the right plastic.
- Guide to Engineering Plastics – Deep dive into material properties and selection.
- CNC Machining Cost Estimator – Estimate run times and labor costs.
- Engineering Unit Converter – Switch between Imperial and Metric easily.
- Plastic Machining Tolerances Guide – Learn about thermal expansion and precision.