PP-TD20 Density Versus Alternative Materials: Buying per Kg or per Piece

Density comparison

PP-TD20 about 1.05-1.12 g/cm³; ABS about 1.05; PC/ABS about 1.13; PC about 1.20; PA6 GF30 about 1.36; PA6 GF50 about 1.56; PPS GF40 about 1.65.

So for identical volume, PP-TD20 is roughly 5-8% lighter than PC/ABS and about 20% lighter than PA6 GF30. Converted to material cost per piece, PP's advantage is larger than the tonne price comparison suggests.

When substitution fails

High strength or high heat required: PP-TD20 tensile strength runs about 25-30 MPa, barely a sixth of PA6 GF30, so the part must be thickened or ribbed and the weight advantage disappears.

Painting or bonding required: PP is non-polar with low surface energy, needing flame or plasma treatment, which adds process cost.

The maths worth doing

Compare piece cost rather than tonne price: piece cost = density × volume × tonne price / 1000 + cycle cost + post-processing + scrap loss.

Fill those in and several seemingly cheap materials turn out worse; conversely a material with a high tonne price such as PA6 GF30 can win because the part can be designed thinner.