Cryogenic Deflashing Standard and Model Selection Guide

How to judge whether your part is suitable, what flash thickness works, and which PG-series machine to choose

NANJING PEGE TECHNO MACHINE CO., LTD  |  Frozen Shot PG Series  |  Technical Guide 2026

Cryogenic deflashing is not a universal process. It works brilliantly on some parts and fails on others, and the difference usually comes down to three measurable factors: material, flash thickness, and part geometry. This guide sets out the standards PEGE applies in production, explains the physical principle behind them, and then walks through machine selection for the PG-series range.

It is written for process engineers, tooling engineers and purchasing managers who need a straight answer before committing to a machine or a trial.

Quick answer Suitable: rubber and elastomers, glass-fibre reinforced engineering plastics, thermoplastic elastomers, and zinc or magnesium die-castings. Flash thickness: under 0.2 mm for rubber, under 0.15 mm for plastics, and under 0.1 mm for silicone. Thinner is always better. Shape: small parts (roughly smaller than a fist), rounded profiles without sharp edges, and flash that is long, thin or hidden in holes and difficult to trim by hand. Not suitable: pure PA, pure PC, ABS, PP, HDPE, ETFE, thin-wall or fragile parts, and parts where the flash is as thick as the body.

 

1. What Parts Are Suitable for Cryogenic Deflashing

Cryogenic deflashing removes mould flash by freezing it until it becomes brittle, then blasting it away with polycarbonate media while the part body stays resilient. The process therefore depends on one condition: the flash must embrittle before the part body does. Everything in this section follows from that single rule.

1.1 Suitable material groups

PEGE machines process three broad material families. Each requires a different temperature setting, and each behaves differently at low temperature.

Material group	Typical materials	Suitability	Practical notes
Rubber and elastomers	NR, NBR, HNBR, CR, EPDM, FKM, ACM, SBR, PU	Excellent	The most common application. Proven on O-rings, gaskets, seals and custom moulded parts.
Silicone (VMQ)	Silicone rubber	Difficult	Requires below -110 C, round robust shapes and flash under 0.1 mm. Lower success rate; sample test essential.
Engineering plastics	PA+GF, PC+GF, POM, PPS, PBT, PET, PEEK, PPSU/PSU, LCP	Good	Glass-fibre reinforcement is normally required. Works best on precision injection-moulded parts with thin flash.
Thermoplastic elastomers	TPU, TPO, TPV, EVA, TPR, TPE	Good	Most TPE grades respond well because of a clear embrittlement differential.
Die-cast metals	Zinc alloys, magnesium alloys	Good	Thin die-cast flash becomes friable at relatively warm settings. The metal body is unaffected.

Suitability ratings reflect PEGE production experience. They are a starting point, not a guarantee. Any new compound should be sample tested before production parameters are fixed.

1.2 Materials that are generally not suitable

The following materials have been verified through years of production as poor candidates. In most cases the flash and the part body embrittle together, so the process cannot selectively remove flash without damaging the part.

• Pure PA (unfilled nylon): becomes over-brittle and risks cracking. Use PA+30%GF instead.

• Pure PC (unfilled polycarbonate): no reliable flash-to-part differential. Use PC+30%GF instead.

• ABS: flash and body harden together, so removal is not selective.

• PP (polypropylene): general-purpose polyolefin with poor low-temperature response.

• HDPE: insufficient embrittlement differential.

• ETFE (Tefzel): not suitable for cryogenic deflashing.

This list is not exhaustive. A material that is not explicitly listed as suitable should always be tested first.

1.3 Typical parts and industries

Beyond material, the part family is a useful first filter. The applications below are routinely processed on PEGE machines.

Industry	Typical parts	Why cryogenic deflashing fits
Automotive	O-rings, oil seals, weather strips, grommets, suspension and PU bumper components	Complex parting lines and hidden flash that manual trimming cannot reach consistently.
Medical	Seals, gaskets, surgical instrument components, implant components	Clean, dry, residue-free finish with no cutting marks and no hand contact.
Electronics	Connectors, bobbins, switches, micro-precision plastic parts	Small parts with fine flash and tight dimensional tolerances.
Industrial and hydraulic	Valve blocks, manifolds, washers, fittings, flexible boots	Internal flash in cross-holes and blind holes is removed in one operation.
Consumer and hardware	Decorative zinc die-castings, enclosures, trim parts	Uniform finish on thin die-cast flash without polishing marks.

2. Flash Thickness Standard

2.1 Why flash thickness decides everything

The process relies on differential embrittlement. A thin section of material cools far faster than a thick section, because it has less thermal mass and a much larger surface area relative to its volume. In a cryogenic chamber, the thin flash reaches its brittle point while the thicker part body is still flexible.

That creates a processing window, typically a few minutes wide, in which the polycarbonate media can crack the frozen flash away without abrading the part. If the flash is too thick, it cools at roughly the same rate as the body, the window closes, and the machine either leaves flash behind or starts removing base material.

This is why flash thickness, not part weight or part count, is the single most important number to measure before selecting a machine.

2.2 Flash thickness limits

PEGE applies the following design standard in production. It is the figure to quote to your tooling team when a mould is being specified or reworked.

Material	Maximum flash thickness	Comment
Rubber and elastomers	< 0.20 mm	PEGE production standard. Thinner flash gives a wider process window and lower nitrogen consumption.
Engineering plastics	< 0.15 mm	Applies to glass-fibre reinforced grades such as PA+GF and PC+GF.
Silicone (VMQ)	< 0.10 mm	Flash must also be non-tacky on the part body, otherwise it will not break away cleanly.
Zinc and magnesium die-cast	Thin flash only	No fixed figure is published because die-cast flash varies by die and alloy. Sample testing is required.

Flash thickness should be measured at the thickest point of the parting line, not at an average. A single thick cavity can dictate the cycle for the whole batch.

2.3 What to do when flash is too thick

Thick flash is a moulding problem, not a deflashing problem. If the parting line exceeds the limits above, the correct sequence is to correct the mould first, or to remove the bulk of the flash mechanically and then use cryogenic deflashing for the final clean-up.

Running a thick-flash part through a cryogenic machine usually produces one of two outcomes: residual flash that fails inspection, or a longer cycle with higher nitrogen consumption that erodes the cost advantage of the process. Neither is a good basis for equipment selection.

2.4 A quick measurement method

• Take a moulded part straight from the tool, before any trimming.

• Measure the flash at the thickest point of the parting line with a micrometer or a profile projector.

• Record the value separately for each cavity, or at least for the worst cavity.

• Compare against the limits in section 2.2 and note the margin.

• If the value is borderline, send samples for a trial rather than relying on the calculation.

3. Part Geometry and Shape Rules

Geometry decides how evenly the media reaches the flash, and how much risk there is of damaging the part. The rules below are the ones PEGE applies when assessing a new part.

Geometric feature	Assessment	Reason
Part fits roughly within a fist	Ideal	Barrel volume is the constraint on output. Small parts mean more pieces per cycle and a lower cost per piece.
Rounded body, no sharp edges or weak angles	Ideal	Media flows around the part without concentrating stress on a thin edge.
Long flash along the parting line	Ideal	A long, thin fin has low thermal mass and breaks away cleanly.
Flash hidden in holes, slots or recesses	Ideal	This is exactly where manual trimming is slowest and least consistent.
Flat, uniform flash within the thickness limit	Ideal	Even cooling and even media impact give a repeatable result.
Thin walls, diaphragms, very thin sections	Caution	If the body is as thin as the flash, both embrittle together and selectivity is lost.
Sharp, delicate edges or fine cosmetic surfaces	Caution	Requires lower wheel speed and shorter cycles; test first.
Holes and cavities smaller than about 0.4 mm	Caution	Polycarbonate media loses its cutting effect in very small openings. Fine features may need a different method.
Metal inserts or bonded dissimilar materials	High risk	Different thermal contraction can loosen inserts or cause delamination during tumbling.
Very soft silicone with fragile edges and tacky flash	High risk	Low success rate even at the coldest settings.

3.1 Size and loading

There is no single maximum part size that applies across the range, because barrel volume differs by model. The practical rule is that parts should be comfortably smaller than the barrel and, for good economics, roughly smaller than a fist. A large part occupies barrel volume that could otherwise hold many small parts, so the cost per piece rises quickly.

Loading also matters. The barrel should not be filled to capacity, because parts need room to tumble and present all surfaces to the media. Overloading is one of the most common causes of incomplete deflashing.

3.2 Shape and edge quality

Rounded parts perform best. Sharp corners and thin protruding features are the first places to suffer damage, because blast media concentrates impact energy on a small area. Where a part has both robust and delicate features, the usual approach is to reduce wheel speed and extend cycle time slightly, then verify on samples.

3.3 Flash location

Counter-intuitively, parts that are difficult to trim by hand are often the best candidates for cryogenic deflashing. Flash that runs through a cross-hole, sits in a recess, or wraps around a complex profile is hard to reach with a knife but is fully exposed to tumbling media.

4. Process Window by Material

Once a part passes the material, thickness and geometry checks, the process window is set by temperature and cycle time. The table below gives the starting range PEGE uses. All PG-series machines operate across -130 C to +50 C, which covers every material group.

Material group	Typical processing temperature	Typical cycle time
Rubber and elastomers	-60 C to -110 C	3 to 10 minutes
Engineering plastics	-60 C to -30 C	3 to 10 minutes
Zinc and magnesium die-cast	-40 C to -20 C	3 to 10 minutes
Silicone (VMQ)	-100 C to -120 C or below	Longer; higher nitrogen consumption

These are starting points, not fixed recipes. Harder compounds embrittle at warmer settings and need less nitrogen; softer compounds need colder settings and more nitrogen. Final parameters are set on samples and then stored as recipes on the machine controller.

Media size is the second adjustment. Smaller media (around 0.75 mm) suits small parts and fine features; larger media (around 1.0 mm) suits heavier parts and thicker flash. Wheel speed and barrel speed are then tuned to balance removal rate against surface protection.

5. Model Selection Guide

The PG-series covers five standard models plus an advanced configuration. Selection is a five-step process, and the machine specification tables that follow let you match a model to your production requirement.

5.1 Five steps to the right model

Step 1 - Confirm material suitability. Check the part against section 1. If the material is on the unsuitable list, stop here.

Step 2 - Measure flash thickness. Compare the worst-case parting line against the limits in section 2.2.

Step 3 - Assess geometry. Use section 3 to identify fragile features, inserts and very small openings.

Step 4 - Calculate daily output. Convert your production plan into kilograms per day, not pieces per day. Barrel capacity and loading density are volumetric, so weight is the comparable unit.

Step 5 - Match capacity and blast capability. Choose the smallest model whose rated output covers your requirement with a reasonable margin, then confirm wheel size and blast speed are adequate for the part weight.

5.2 Model comparison: capacity and output

Model	Barrel capacity	Effective capacity	Blast wheel	Blast speed	Reference output
PG-40T	40 L	15 L	250 mm	105.7 m/s	150 - 200 kg/day
PG-60T	60 L	20 L	250 mm	105.7 m/s	200 - 250 kg/day
PG-80T	80 L	30 L	300 mm	123.3 m/s	250 - 300 kg/day
PG-120T	120 L	40 L	350 mm	145.3 m/s	400 - 500 kg/day
PG-150T	150 L	50 L	350 mm	105.7 m/s	500 - 600 kg/day

Reference output is based on typical loading and cycle time. Actual output depends on part weight, loading density, flash thickness and the cycle required for your material.

5.3 Model comparison: electrical and dimensions

Model	Power	Wheel speed	Dimensions (L x W x H)	Weight
PG-40T	4 kW	3000 - 7200 rpm	1080 x 960 x 1460 mm	500 kg
PG-60T	6 kW	3000 - 7200 rpm	1000 x 1000 x 1950 mm	700 kg
PG-80T	7 kW	3000 - 7000 rpm	1100 x 1200 x 2000 mm	850 kg
PG-120T	8 kW	3000 - 7200 rpm	1200 x 1250 x 2200 mm	1000 kg
PG-150T	9 kW	3000 - 7000 rpm	1300 x 1350 x 2250 mm	1500 kg

All models: power supply AC 380 V, 50/60 Hz, 3 phase; cooling range -130 C to +50 C; cooling media liquid nitrogen; blasting media polycarbonate granule; barrel speed 0-25 rpm; touch screen operation.

5.4 Selection by daily output

If your requirement is already expressed in kilograms per day, the table below gives a direct starting point. Choose the model whose range covers your normal production day, then check whether peak days can be absorbed by extra shifts rather than by a larger machine.

Required output	Recommended model	Typical fit
150 - 200 kg/day	PG-40T	Small parts, multi-material workshops, sample and trial work, cost-sensitive buyers.
200 - 250 kg/day	PG-60T	Single-product lines with moderate volume; the most common entry point for rubber parts.
250 - 300 kg/day	PG-80T	Mixed production with medium parts; a good balance of capacity and floor space.
400 - 500 kg/day	PG-120T	High-volume production, larger parts, and PU bumper or large moulded components.
500 - 600 kg/day	PG-150T	Continuous high-volume lines and the largest parts in the range.

5.5 Selection by part and batch profile

• Small parts, high piece count: PG-40T or PG-60T. A smaller barrel filled efficiently usually beats a large barrel running half empty.

• Medium parts, mixed materials: PG-80T. The 300 mm wheel and higher blast speed handle heavier parts without extending the cycle.

• Large moulded parts or PU bumpers: PG-120T. This is the model PEGE specifies for polyurethane bumper applications.

• Continuous three-shift production: PG-150T, with the 50 L effective capacity reducing the number of cycles per shift.

• Frequent material changeovers or trial work: PG-40T. Its small chamber volume keeps cool-down fast and nitrogen use low during short runs.

6. Worked Examples

The parameter sets below are real production references. They show how the general rules translate into settings for three different material families.

Example 1 - NBR O-rings on PG-80T

Part: NBR O-ring, 2 mm inside diameter, 20 mm outside diameter.

Parameter	Setting
Temperature	-75 C
Blasting time	5 minutes
Media size	1.0 mm polycarbonate
Blasting speed	6,000 rpm
Barrel speed	20 rpm
Load per cycle	approximately 3.5 kg

This configuration delivers clean flash removal with no surface damage. It is a good baseline for small rubber seals.