How Dry Ice Makes Shrink Fitting Easier: A Guide for Maintenance Professionals

When you need to fit a bearing onto a shaft or insert a bushing into a housing with an interference fit, you have a few options: press it in with force (and risk damage), heat the outer part (which requires specialized equipment and can be tricky), or cool the inner part to make it temporarily smaller. That's where dry ice comes in.

At Greco Gas, we supply dry ice to machine shops, maintenance departments, and industrial facilities throughout Southwestern Pennsylvania who use it for shrink fitting. It's a straightforward, effective method that's been around for decades—but not everyone knows about it.

What Is Shrink Fitting with Dry Ice?

Shrink fitting is an assembly method where you create a tight interference fit between two metal parts by temporarily changing their size through temperature. When metal gets cold, it contracts. When it warms back up, it expands.

Here's the basic process:

1. You submerge the inner component (shaft, bearing race, bushing, gear, etc.) in dry ice or pack dry ice around it
2. The part cools to around -109°F (-78.5°C) and contracts
3. While cold, it slides easily into place
4. As the part warms back to room temperature, it expands and creates a tight, secure fit

No pressing equipment needed. No heating torches. No risk of damaging bearing seals or warping components.

Who Uses Dry Ice for Shrink Fitting?

We see this application across several industries:

Manufacturing and machine shops use it for assembly operations—installing bearings on motor shafts, fitting bushings into housings, and assembling gearboxes.

Maintenance and repair facilities keep dry ice on hand for equipment repairs. When you need to replace a bearing on a production line, speed matters. Dry ice gets the job done quickly.

Industrial facilities with in-house maintenance teams use it for everything from pump repairs to conveyor system maintenance.

Automotive and heavy equipment repair shops use it for driveline work, transmission rebuilds, and differential repairs.

Why Dry Ice Works Better Than Other Methods

No specialized equipment required. You don't need a hydraulic press or heating equipment. A cooler and some dry ice will do the job.

It's safer for the parts. Heating the outer component can damage seals, affect heat treatment, or cause warping. Cooling the inner part avoids these issues.

It's faster. Parts cool down in minutes, not hours. And since you're not heating anything, there's no waiting for things to cool down before you can handle them.

Better control. Unlike liquid nitrogen (which gets even colder but requires special storage), dry ice is easier to handle and gives you enough temperature drop for most shrink fitting applications without going overboard.

It's predictable. Metal contracts at a known rate. For steel, you get roughly 0.001 inches of contraction per inch of diameter for every 100°F of temperature drop. That means a 2-inch shaft cooled from 70°F to -100°F will shrink by about 0.0034 inches—often enough to turn an interference fit into an easy slip fit.

How to Use Dry Ice for Shrink Fitting: Practical Tips

Use pellets or blocks. Dry ice pellets work well because you can pack them around irregular shapes. Blocks are fine if you're submerging parts in a cooler.

Give it time. Small parts might be ready in 10-15 minutes. Larger, heavier components can take 30-60 minutes to fully cool. The metal needs to reach temperature all the way through, not just on the surface.

Keep parts dry. Moisture in the air will freeze on cold metal surfaces. This frost layer can affect the fit. Work in a dry environment when possible, and wipe parts down with a dry cloth right before assembly.

Have everything ready before you start cooling. Once the part reaches temperature, you need to work quickly. Don't start cooling until your housing is clean, properly aligned, and ready to receive the cold part.

Wear proper gloves. Dry ice will freeze skin on contact. Insulated gloves rated for cryogenic temperatures are worth having.

Work in a ventilated area. Dry ice is solid CO2. As it sublimates, it displaces oxygen. In a small, enclosed space, that matters. Adequate ventilation is important.

Calculate your interference. If you know your interference fit dimension and the temperature drop, you can calculate whether dry ice will give you enough contraction. For most bearing installations, it will. For very tight fits, you might need liquid nitrogen instead.

When Dry Ice Might Not Be the Right Choice

Dry ice doesn't work for everything. If you're working with aluminum (which contracts more than steel), you need to be more careful with clearances. If you're dealing with extremely tight tolerances, liquid nitrogen gives you more temperature drop. And if you're heating the outer part anyway (because it's easier to access), there's no reason to cool the inner part.

But for standard bearing installations, bushing replacements, and most gear assemblies, dry ice hits the sweet spot of being cold enough to work, but not so cold that it requires special handling equipment.

Why We Keep Dry Ice in Stock for Industrial Customers

Some of our customers use dry ice occasionally—when a repair comes up. Others go through it regularly for production work. Either way, we stock it because we know maintenance work doesn't happen on a schedule.

We produce dry ice at our facility in Tarentum and have available stock in Butler and Kittanning. That means we control quality and availability. You're not depending on a third-party supplier who might or might not have inventory when you need it.

Same-day availability for customers in the Pittsburgh area and Southwestern Pennsylvania. Call us in the morning, pick it up in the afternoon. 16mm. dry ice pellets are always in stock. A pre-order is required for blocks/slabs

Pellets or block/slabs, depending on your application. We have a 50lbs. minimum for blocks/slabs.

Low minimum order. Take what you need. If you only need 10 pounds for a single repair job, that's fine. We have a 5lbs. minimum for 16mm. pellets

Large Insulated storage containers are available for rent if you are ordering high quantities of dry ice - 100lbs or greater.

Getting Started with Shrink Fitting

If you're new to using dry ice for shrink fitting, start with a non-critical application to get comfortable with the process. Try it on a bearing replacement where you'd normally use a press. You'll quickly see why maintenance professionals who discover this method keep coming back to it.

We're here to answer questions about quantities, storage, and handling. Give us a call at any of our three locations, and we'll help you figure out what you need.

Greco Gas serves Pittsburgh and Southwestern Pennsylvania with locations in Tarentum, Butler, and Kittanning. We produce and supply dry ice, along with industrial gases, medical gases, propane, and welding supplies. For same-day dry ice availability or questions about industrial applications, contact us.