The colour was spot on last week. This week, it’s slightly off. Nothing has changed on the machine, and the masterbatch is the same one. Yet the parts don’t quite match.

Colour drift is one of the most common quality complaints in injection moulding. Here are the usual causes, and where to look first.

Why Colour Drift Is So Hard to Pin Down
Colour is affected by several things at once. Dosing accuracy, material condition, processing temperature, and residence time all play a part. A small change in any one of them can shift the final shade, often by an amount that’s hard to see until two parts sit side by side.

That’s why colour problems tend to be blamed on the masterbatch first. In our experience, the masterbatch is rarely the real culprit.

Common Causes We See on Site

1. Dosing Inaccuracy
   This is the most frequent cause. If the amount of colourant added varies, even slightly, the colour will vary with it. Worn dosing screws, a feeder that’s drifted out of calibration, or masterbatch that bridges in the hopper can all cause the dose to wander over a long run.
2. Poor Mixing
   Colourant and base material need to blend evenly before they reach the screw. If they separate on the way, you get streaking or patchy colour. Material of different pellet sizes is particularly prone to this, since the smaller pellets settle out of the mix.
3. Inconsistent Base Material
   If the base resin isn’t consistent, the colour won’t be either. Moisture is a common offender. A dryer that isn’t hitting spec can change how the material processes, and that can shift the shade. See our article on common causes of inconsistent moulded parts for more on this.
4. Regrind Variation
   Regrind carries the colour of its previous life. If the regrind ratio changes, or the regrind comes from a slightly different colour batch, the final colour moves with it. Keeping regrind traceable matters as much for colour as it does for contamination.
5. Processing Temperature and Residence Time
   Some pigments change shade when they’re overheated or held in the barrel for too long. If cycle times stretch, or the barrel runs hotter than planned, the colour can shift even though the dosing hasn’t changed.

How to Track It Down
Work through the likely causes in order, starting with the simplest checks:

• Check the dosing rate against the set point, not just whether the doser is running
• Look for bridging or blockages in the masterbatch hopper
• Confirm the base material is within moisture spec
• Check the regrind ratio and where the regrind came from
• Compare barrel temperatures and cycle time against a known good batch
• Keeping Colour Consistent
• The most reliable fix is accurate, repeatable dosing. A well-specified doser, kept calibrated, removes the biggest single source of colour variation. Our range of colour dosers is chosen to suit your material, throughput and colour change frequency.

It also helps to log dosing rates and regrind ratios against each batch. When colour does drift, a record makes it much quicker to find out why.

Get in Touch
If colour consistency has become a problem on your line, we’re happy to talk it through. Sometimes it’s a quick calibration check. Sometimes it’s worth looking at the dosing equipment itself.

Geiger Handling UK Ltd
Phone: 01782 630555
Email: sales@geigerhandling.co.uk
Web: geigerhandling.co.uk

A granulator with worn blades doesn’t usually stop working. It just does the job worse, a little at a time, until someone notices the regrind doesn’t look quite right anymore.

Here’s how blade wear actually affects your process, and how to tell when it’s time to replace them rather than push them a few more weeks.

Why This Gets Missed

Blades wear gradually, not all at once, so there’s rarely a clear moment where performance drops off a cliff. A granulator running on worn blades still produces regrind. It just takes longer, uses more energy, and produces a less consistent result than it should.

Because the machine keeps running, blade condition often only gets checked once something else goes wrong, rather than on a proper schedule of its own.

How Blade Wear Actually Shows Up

1. Inconsistent Particle Size

Sharp blades cut cleanly. Worn ones tear and crush more than they cut, producing a wider mix of particle sizes rather than the consistent regrind a process needs. This ties directly into what we’ve covered before on material contamination — inconsistent regrind is one of the more common contributors to it.

2. More Fines

Worn blades generate a higher proportion of fine dust and small particles rather than uniform granules. Excess fines cause their own downstream problems, including the kind of vacuum loader blockages we’ve written about separately.

3. Higher Energy Use

A dull blade needs more force to cut through the same material. The motor works harder for the same throughput, which shows up as a steady creep in energy use rather than a sudden spike.

4. Increased Noise and Heat

Worn blades generate more friction than a clean cut. A granulator running noticeably louder or hotter than usual is often telling you something about blade condition before it shows up anywhere else.

5. Slower Throughput

As cutting efficiency drops, material takes longer to process to the right size. What used to be a quick job starts taking noticeably longer, even though nothing about the material or the machine’s settings has changed.

What to Check

Inspect blade edges directly for visible dulling, chipping, or uneven wear rather than relying on how the machine sounds alone. Compare current energy readings or cycle times against what’s normal for the machine, if you have that data to hand. A steady drift in either is often the clearest early signal.

Getting the Most from a Granulator

Blade sharpening or replacement on a proper schedule, rather than waiting for regrind quality to visibly suffer, keeps particle size consistent and energy use predictable. It’s a small, routine cost compared to the knock-on effect of feeding inconsistent regrind back into your process.

Our range of granulators is specified against the material and throughput you’re actually running, and we can advise on blade maintenance schedules suited to your specific setup.

Get in Touch

If your granulator’s regrind quality has drifted, or you’re not sure whether your blades are due attention, we’re happy to take a look.

Geiger Handling UK Ltd
Phone: 01782 630555
Email: sales@geigerhandling.co.uk
Request a quote: Here

Drying is one of the more energy-hungry stages of the injection moulding process, and it’s not always obvious how much a more efficient dryer would actually save until you put real numbers against it.

qip GmbH, one of our material drying partners, has put together a savings calculator that does exactly that. It’s a genuinely useful five-minute exercise if you’re weighing up whether a compressed air dryer makes sense for your process.

Why Compressed Air Drying Is Different

Most conventional dryers use refrigeration or desiccant regeneration to remove moisture from the air before it reaches the material. Both work, but both carry a real energy cost, running more or less continuously to keep drying air at the right dew point.

qip’s dryers take a different approach. They use compressed air already available on most factory floors, rather than generating dried air from scratch. Their ID-BD and CD-TD series are built for this, with hopper volumes from small desktop units up to 170 litres. They’re designed to mount directly onto the production machine.

What the Calculator Actually Estimates

The qip savings calculator lets you enter details about your current setup. It then estimates the potential difference a compressed air dryer could make. Go in with your own figures to hand — current dryer type, running hours, and material throughput — so the result reflects your actual process, not a generic average.

The value here isn’t treating the output as a guaranteed number. It’s getting a realistic starting point for whether the conversation is worth having at all.

Who This Is Worth Looking At For

If you’re running a conventional desiccant or refrigerant dryer continuously, this is worth five minutes of your time. That’s especially true on smaller machines or lower throughput lines. It’s also worth a look if you’ve been searching for ways to cut energy costs more broadly. Drying is often a bigger contributor to a factory’s energy bill than people expect.

This ties into a point we’ve made before about material handling being one of the foundational stages that shapes both quality and cost further down the line. Drying efficiency is very much part of that picture.

Get in Touch

If you run the numbers and want to talk through whether a compressed air dryer is a good fit for your setup, we’re happy to help. We work with qip as one of our material drying partners and can advise on what would actually suit your process.

Geiger Handling UK Ltd
Phone: 01782 630555
Email: sales@geigerhandling.co.uk
Web: geigerhandling.co.uk

If you’re running several machines on individual loaders, a central conveying system is probably a familiar idea, even if you haven’t looked into it properly yet. Here’s how one actually works, and where it tends to make the biggest difference.

What a Central Conveying System Actually Does

Instead of each machine having its own loader and its own material source, a central system does it differently. Material moves from one or more bulk storage points, through a shared network of lines, to multiple machines at once.

One vacuum pump, or a small number of them, does the work that would otherwise need a separate loader per machine. A manifold routes material to each drop point, with selection valves sending the right material to the right machine.

The Basic Flow

• Bulk storage. Material sits in silos, bulk bags, or gaylords rather than smaller day-hoppers at each machine.
• Central pump station. One or more vacuum pumps draw material through the line network on demand.
• Manifold and valves. Material is routed to the correct machine or hopper, often switching between multiple material types across the system.
• Drying, where needed. Material can be dried centrally before distribution, or at the point of use, depending on how the system’s designed.
• Delivery to the press. Material arrives at each machine’s hopper, topped up automatically as it’s consumed.

Where It Makes the Biggest Difference

Shops running six or more machines tend to see the clearest return. Fewer individual loaders means less kit to maintain. Bulk buying material also gets much easier once storage isn’t limited to what fits next to each press.

It cuts manual handling too. Bags aren’t cut open and tipped by hand at every machine, which reduces labour and one of the most common sources of contamination on a busy shop floor.

What to Check Before Switching

A central system costs more upfront than a set of individual loaders. It needs proper planning around line runs, how often materials change over, and how many different materials share the same network. Get the design wrong, and you risk the same problems individual loaders have, just on a bigger scale — including blockages, if line runs are too long or badly routed.

Our conveying systems range is designed and specified around your actual shop floor layout, rather than a generic setup.

Get in Touch

If you’re weighing up whether a central system makes sense for your shop, we’re happy to talk through the numbers properly before you commit to anything.

Geiger Handling UK Ltd
Phone: 01782 630555
Email: sales@geigerhandling.co.uk
Web: geigerhandling.co.uk