ABS moulds at 1.04-1.06 g/cm³ with 40-50 MPa tensile strength, a heat deflection temperature near 95-100 °C and shrinkage of 0.5-0.7%. SkillsProto builds aluminium tools in 7-10 days and steel tools in 15-25 days, works to ±0.05 mm on most moulded features, and ships DDP to the UK, EU and US in 3-5 days. A first article inspection report ships with the first parts, CMM data is available on request, and quotes with DFM feedback return within 24 working hours.
ABS properties at a glance
ABS is a terpolymer of acrylonitrile, butadiene and styrene. The butadiene phase gives impact toughness, the styrene phase gives a glossy surface and easy processing, and the acrylonitrile phase gives chemical and heat resistance. That balance is why ABS is the default choice for housings, enclosures, consumer product shells and automotive interior trim.
| Property | ABS | PC | PP | PA6 / PA66 | POM |
|---|---|---|---|---|---|
| Density | 1.04-1.06 g/cm³ | ~1.20 g/cm³ | ~0.90 g/cm³ | 1.13-1.15 g/cm³ | ~1.41 g/cm³ |
| Tensile strength | 40-50 MPa | 60-70 MPa | 25-40 MPa | 60-80 MPa | 60-70 MPa |
| Heat deflection temperature | 95-100 °C | 130-140 °C | 90-110 °C | 150-200 °C filled | 100-120 °C |
| Shrinkage | 0.5-0.7% | 0.5-0.7% | 1.0-2.5% | 0.8-1.5% | 1.8-2.5% |
| Impact strength | Good | Excellent | Good | Moderate | Moderate |
| Chemical resistance | Poor against solvents | Fair | Good | Fair | Good |
| Plating and painting | Excellent | Poor without primer | Poor without treatment | Poor | Poor |
| Bonding and welding | Easy with solvent or adhesive | Easy | Difficult | Difficult | Difficult |
ABS sits in the middle of the table on every axis except finishability, where it beats all four alternatives. It is the only common moulding resin that can be electroplated directly, which is why it remains the standard substrate for chrome-look trim and appliance bezels.
Tolerances and shrinkage
SkillsProto works to ±0.05 mm as the general tolerance on ABS mouldings, and to ±0.005 mm on features that are CNC-machined after moulding or used as machined datums. Shrinkage is the variable that dominates everything else: at 0.5-0.7%, a nominal dimension drifts by a fixed percentage, and the spread between the low and high end of that range is what the tool has to absorb.
| Nominal size | Shrinkage at 0.5% | Shrinkage at 0.7% | Spread to control |
|---|---|---|---|
| 25 mm | 0.125 mm | 0.175 mm | 0.05 mm |
| 50 mm | 0.25 mm | 0.35 mm | 0.10 mm |
| 100 mm | 0.50 mm | 0.70 mm | 0.20 mm |
| 200 mm | 1.00 mm | 1.40 mm | 0.40 mm |
A 100 mm housing therefore varies by up to 0.20 mm depending on where in the process window it was moulded — four times the ±0.05 mm tolerance band. SkillsProto scales the cavity with a shrinkage factor confirmed on the first shots, then verifies the result in the first article inspection report. Where a bore or datum must sit inside ±0.05 mm regardless of shrinkage, the answer is a machined post-operation, not a tighter mould.
Tooling options: aluminium vs steel
| Factor | Aluminium tool | Steel tool |
|---|---|---|
| Build time | 7-10 days | 15-25 days |
| Typical tool life | Hundreds to low thousands of shots | 100,000+ shots |
| Economic quantity | 100-5,000 parts | 5,000 parts and up |
| Cycle time | Often faster, aluminium conducts heat well | Standard |
| Design changes | Cheap and quick | Expensive, slow |
| Best used for | Pilot runs, market testing, bridge production | Programmes with stable design and long life |
Aluminium tools are the right answer for most enquiries below 5,000 parts: they cut 8-15 days out of the schedule and absorb design changes without a second tool. Steel pays off once the design is frozen and the volume justifies the longer build. SkillsProto quotes both options with the same DFM feedback so the break-even quantity is visible in numbers rather than assumed.
Cost drivers
| Driver | Typical effect on programme cost |
|---|---|
| Cavity count | Going from 1 to 2 cavities adds roughly 40% to tooling but cuts piece price close to 40% |
| Wall thickness | 3.0 mm walls instead of 2.0 mm add about 50% material and 20-30% cycle time |
| Side actions and undercuts | Each adds roughly 15-25% to tooling cost |
| Cosmetic class | Polished or textured cavity surfaces add 10-20% to tooling |
| Colour and resin grade | Custom colour or grade adds 3-5 days to the schedule |
| Tolerance callouts | Every dimension below ±0.05 mm adds measurement and scrap cost |
Part geometry, not resin price, decides most ABS programmes. A 2.0 mm uniform wall with ribs instead of a 3.5 mm solid wall typically removes 30-40% of the material and shortens the cycle enough to change the piece price more than any resin negotiation will.
Design rules: wall thickness, ribs, draft
- Wall thickness of 1.2-3.5 mm, with 2.0-2.5 mm the target for most housings; uniform walls prevent sink and warp.
- Rib thickness at 0.5-0.7x the nominal wall, so a 2.5 mm wall takes ribs of roughly 1.3-1.8 mm.
- Rib height limited to about 3x the wall thickness, with 0.5-1.0 mm radii at the rib base.
- Draft of 1-2° per side on all vertical faces; 3° or more on textured surfaces.
- Boss outer diameter at 2x the screw hole diameter, with the boss tied to the wall by ribs rather than standing free.
- Corner radii of at least 0.5x wall thickness inside and outside, to keep melt flow even and stress low.
- Gate location on a non-cosmetic, thick section, so the part fills from thick to thin.
- Shrinkage compensation applied in the cavity before cutting steel or aluminium, using the 0.5-0.7% range.
Finishes for ABS
| Finish | Result | Added lead time |
|---|---|---|
| As-moulded, SPI finish | Gloss or matte directly from the cavity | 0 days |
| Electroplating | Chrome-look metal layer, ABS is the standard substrate | +5-8 days |
| Spray painting | Colour matched, single or two-coat | +3-5 days |
| Silk screen or pad print | Logos and legends | +2-3 days |
| Laser marking | Permanent marks, no consumables | +1-2 days |
| Texture (VDI or MT) | Mould-textured surface, hides flow lines and wear | +3-5 days to tooling |
Electroplating is the reason many programmes stay on ABS: PC, PP and POM all need primers or special treatments to take a metal layer, while ABS plates directly. Texture is the cheapest way to hide sink marks and flow lines on large cosmetic faces, and it should be specified before the cavity is cut, not after.
When to switch material
| Requirement | Switch to |
|---|---|
| Continuous service above 100 °C, or impact above ABS range | PC |
| Chemical exposure, solvents, acids, living hinges | PP |
| Sliding wear, bearings, gears | PA6, PA66 or POM |
| Dimensional stability with low creep | POM |
| 10-500 parts and no tooling budget | Vacuum casting |
| 500 parts and up in metal | Die casting |
| Design still changing, 1-50 prototypes | 3D printing |
SkillsProto runs ABS tooling, vacuum casting, 3D printing and die casting in the same facility, so the same part can move between processes as volume rises without a new supplier conversation.
Frequently Asked Questions
What shrinkage should I expect from ABS?
ABS shrinks 0.5-0.7%. On a 100 mm dimension that is 0.50-0.70 mm of movement, and the 0.20 mm spread across the range is larger than the standard ±0.05 mm tolerance band. SkillsProto applies a shrinkage factor to the cavity, confirms it against the first shots and records the result in the first article inspection report.
How tight can ABS injection moulding tolerances be?
±0.05 mm is the general working tolerance on ABS mouldings. Features that must be tighter than that are machined after moulding, where ±0.005 mm is available. Tight callouts should be limited to functional dimensions: every extra tight dimension raises measurement time and scrap cost.
Do I need an aluminium tool or a steel tool?
Aluminium tools take 7-10 days and suit 100-5,000 parts, design changes and bridge production. Steel tools take 15-25 days and suit programmes past 5,000 parts with a frozen design. SkillsProto quotes both against the same DFM feedback and states the break-even quantity.
How long does ABS tooling take at SkillsProto?
Aluminium tooling is built in 7-10 days and steel tooling in 15-25 days. First parts ship with a first article inspection report, DDP delivery to the UK, EU and US takes 3-5 days, and quotes with DFM feedback arrive within 24 working hours.
Can ABS parts be plated or painted?
Yes. ABS is the standard substrate for electroplating and takes chrome-look finishes without a primer, unlike PC, PP or POM. Plating adds 5-8 days, spray painting 3-5 days, and textured or polished cavities add 10-20% to tooling cost. Silk screen, pad print and laser marking are also available.
What quantities make sense for ABS injection moulding?
Aluminium tooling becomes economical from roughly 100 parts and covers up to about 5,000. Below 100 parts, or while the design is still changing, 3D printing at 2-4 days or vacuum casting at 10-500 pieces usually costs less in total. Above 5,000 parts with a stable design, steel tooling is the lower-cost route per part.
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