Choosing the Right Ejection Rubber for Die Cutting: A Practical Guide

If you’ve ever had a die cutting job go sideways—material sticking in the die, inconsistent cuts, or a rule that just won’t release—there’s a good chance the ejection rubber wasn’t doing its job. It’s one of those small components that rarely gets attention until something goes wrong, yet it directly affects how smoothly your press runs and how long your die lasts.

So how do you pick the right ejection rubber? It’s not just about grabbing whatever is closest on the shelf. The right choice depends on your material, your die layout, and how fast you’re running. Let’s walk through the key points without overcomplicating it.

Hardness matters more than you think

Ejection rubber comes in different hardness levels, usually measured in Shore A. The general rule is simple: softer rubber compresses more easily and works well for delicate materials, while harder rubber rebounds faster and is better for dense die layouts or high-speed cutting.

For most standard paperboard and cartons, a hardness between 30 and 45 Shore A is a safe bet. If you’re cutting corrugated board, you might want something a bit softer—25 to 35 Shore A—so the rubber absorbs the compression without putting too much stress on the board. When your die has a lot of rules packed closely together, moving up to 45–55 Shore A helps the rubber stay in place instead of getting pushed sideways.

A common mistake is choosing rubber that’s too hard. It seems like it would eject faster, but it can actually damage the material or put unnecessary pressure on the die. On the other hand, too soft and the rubber may not return to its original height quickly enough, leading to material jams.

Many suppliers color-code their ejection rubber by hardness, which makes it easy to grab the right one once you know what works for your job.

Material options: open cell, closed cell, and beyond

Traditional open cell rubber is still widely used for flat die cutting. It’s affordable and does the job, but it tends to break down over time and lose its bounce. Closed cell rubber lasts longer and resists compression set better, making it a good choice for higher-speed applications.

More recently, microcellular polyurethane has become popular because it holds its thickness tolerance very tightly and doesn’t deteriorate the way open cell does. It costs a bit more, but if you’re running large volumes, the consistency can pay off.

EVA foam is another lightweight option, often used for cardboard and corrugated work. It’s versatile and easy to handle, though it may not last as long as polyurethane in demanding jobs.

Installation: small details, big impact

Where you place the ejection rubber and how tall it is can make or break your die cutting. You want the rubber positioned on both sides of the cutting rule, as close as possible without interfering with the cut. If it’s too far away, it won’t eject properly; too close, and it might get nicked by the rule.

Height is another factor. The rubber should sit slightly taller than the exposed rule so it can compress and still push the material off. A little extra height also compensates for compression set over time, so you get more life out of each piece.

In areas where rules are densely packed, consider using a trapezoidal or arched profile to reduce lateral movement. Mixing different hardness levels across the die board—harder where rules are tight, softer where there’s more space—can also improve performance.

Before applying the self-adhesive rubber, make sure the die board is clean and dry. Any dust or oil will weaken the bond, and you don’t want rubber popping off mid-run.

When to replace your ejection rubber

Ejection rubber is a wear item, so eventually it needs to be replaced. The signs are usually pretty clear: if the rubber doesn’t spring back to its original height after compression, it’s lost its ejection force. If the hardness has dropped noticeably—you can check with a durometer—it’s time to swap it out. For most standard paperboard jobs, you’ll get somewhere between 300,000 and 400,000 impressions before replacement is needed. Checking the durometer every 100,000 impressions is a good habit to build into your maintenance routine.

If only a few pieces are damaged, you can replace just those. But if most of the rubber has aged and the hardness is all over the place, redoing the whole die board will give you more predictable results.

Getting the right ejection rubber for your shop

We supply ejection rubber in a full range of hardness levels, from 20 to 70 Shore A, in open cell, closed cell, microcellular polyurethane, and EVA foam. Sheets, strips, and custom pre-cut profiles are all available, and we keep tight tolerances on thickness so you get consistent performance.

If you’re not sure which hardness or material fits your job, send us a message with your die cutting details. We’re happy to recommend the right option and can send free samples so you can test before committing to a bulk order.