How Heavy Machinery Relies on Both Hard Chrome and Electroless Nickel Plating to Keep Running at Its Best

Heavy machinery relies on both hard chrome and electroless nickel plating from premature wear that causes downtime and production loss. Even though both of these finishes protect the substrate metal, each has an area of expertise. Hard chrome plating is best served on sliding components like hydraulic cylinder rods and piston rods. Electroless nickel plating has a unique task: It covers complex-geometry parts like valve bodies and pump housings where uniform coating is essential. Which one do you choose for heavy machinery? Let’s take a closer look.

The Cost of Unprotected Metal

If you have ever watched a hydraulic cylinder fail in the field, you know that work stops, or significantly slows down. If any of your components are uncoated and you don’t have any spare components ready to be installed in its place, the set backs add up quickly.

Unprotected or uncoated rod deteriorates from friction, moisture and the constant scraping of seals eat away at the bare steel quickly. This is where surface plating comes in handy. Surface coatings for both hard chrome plating and electroless nickel plating protects the surface metal from wear on the substrate itself. For heavy machinery operating in mining, construction, agriculture, and oil and gas, longevity is a necessity.

This doesn’t mean the surface coatings don’t get worn down over time, it still does. But it takes much longer to occur, and when it gets close to the steel metal, change out the component and get your components repaired for reuse. This saves on the cost of constant brand new purchases with very long wait times.

The Ultimate Protector for Heavy Machinery

Hard chrome plating is an electroplating process that deposits a layer of chromium onto a metal substrate using an electrical current and a chromic acid bath. The hard chrome plating is applied all at once, meaning half of it gets plated, and then the other half gets plated causing a seam to occur. Plating specialists such as EN-CHRO Plating has bath’s large enough for a full size rod to be fully submerged. Once completed and the component is tested by our Quality Assurance department, you’ll find that the hardness is between 68 and 72 on the Rockwell C scale.

Hard chrome can be applied in thicknesses ranging from 0.0005 inches all the way to 0.010 inches and beyond, depending on the application and components. Thinner deposits are used when dimensional tolerances are tight. Heavier deposits are used for parts that need to be built up after wear or damage.

The hard chrome plating process also creates a low coefficient of friction, which means less heat generated during sliding contact and less energy lost to resistance. This is why heavy machinery relies on both hard chrome and electroless nickel plating for sliding components.

The Parts Hard Chrome Plating Protects in Heavy Machinery

In heavy machinery, hard chrome plating is used often on the components that carry the highest loads and move the most whether it be fast or slow.

Hydraulic Cylinder Rods and Piston Rods

Hard chrome plating is the preferred choice for hydraulic cylinder rods. These rods extend and retract thousands of times over a machine’s service life, sliding through seals while carrying enormous loads. The hard chrome plated surface protects against seal wear, corrosion from moisture and chemicals, and the mechanical abrasion of contaminants.

Piston rods on excavators, bulldozers, loaders, and cranes share the same demands. Other industries that use hydraulic rams are on presses and jacks.

Pump Shafts, Gear Shafts, and Machine Tool Components

Pump shafts and sleeves can also benefit from hard chrome plating when they run against bushings or packings. Gear shafts that also slide, use the same protection against galling and surface fatigue. For a machine tool spindle surface, when it wears, tolerances open up. Quality suffers. Keeping the chrome surface intact directly supports production consistency.

Shock Absorber Components

Shock absorber bodies and rods, including those on large industrial and heavy automotive applications, are another important category. The surface sees dynamic loading, heat cycling, and seal contact all at once. Hard chrome plating can handle that combination with durability and stability.

How EN-CHRO Plating Handles Hard Chrome Work

EN-CHRO Plating, based in Melrose Park, Illinois, has spent more than 40 years solving surface coating engineering challenges across a wide range of industrial industries. The hard chrome plating capabilities cover both inside diameter and outside diameter surfaces, handling large and complex parts for small production runs as well as large batches.

Thickness options range from flash chrome for delicate precision applications up through heavy buildup deposits for restoration work. EN-CHRO Plating can also perform heat treatment for automotive shock absorber components, with equipment that accommodates parts up to eight feet in length.

When a component comes in to our facility that has been previously hard chrome plated and needs to be repaired, the team first performs an analysis understanding what needs to be repaired, which areas need to be stripped and does it need to be polished. Based on the results, the team uses a chemical-based removal process to strip the existing coating cleanly before repairs can begin.

What Electroless Nickel Plating Does Differently

Electroless nickel plating is also a protectant and allows the components to last longer, but its used in different applications. The process relies on a chemical reaction between a nickel salt solution and a reducing agent, most commonly sodium hypophosphite, to deposit nickel directly onto the part surface.

Because the deposition is driven by chemistry rather than electricity, the coating builds up at the same rate at the same time everywhere on the part such as inside a bore, down a threaded section, around a corner and into a recessed pocket. The thickness at the bottom of a complex cavity matches the thickness on the outer surface. That’s the benefit of electroless nickel plating.

Phosphorus Content and What It Changes

The phosphorus content of the bath determines the properties of the deposit. High-phosphorus formulations, running above 10 percent phosphorus, deliver maximum corrosion resistance and is a perfect choice for acidic or aggressive chemical environments. Medium-phosphorus baths, in the 5 to 9 percent range, offer a balance of wear resistance, hardness, and corrosion protection.

Electroless nickel lands in the RC 48 to 52 range on the Rockwell C scale. When the components demand more, a heat treatment step at 750 degrees Fahrenheit can be used to increase the hardness up to RC 68 to 70. This hardness is within the same area as hard chrome.

The Parts Electroless Nickel Plating Protects in Heavy Machinery

For heavy machinery, electroless nickel plating is the best choice when the shape is complex or harsh chemicals are used.

Valve Bodies and Pump Components

Valve bodies and internal valve components are great examples for electroless nickel plating. Valves have threaded ports, internal passages, and complex bore geometries. The purpose of electroless nickel plating is to evenly coat all the nooks and crannies of the component so each area is the same thickness as the next.

Pump housings and impellers, particularly in chemical processing and oil and gas applications, benefit from the corrosion barrier that high-phosphorus electroless nickel builds up. The coating seals the base metal from the aggressive media flowing through it.

Molds, Dies, and Bearing Housings

Molds and dies used in heavy manufacturing use electroless nickel plating as it reduces friction at the mold surface, helps in the parts release, and extends the interval between polishing and maintenance cycles, which keeps production lines moving.

Bearing housings are plated where dimensional precision on complex shapes. Dry bulk material handling equipment, including conveyor components and chutes, benefits from the wear and corrosion protection the coating provides in abrasive, high-humidity conditions.

Threaded Components and Food-Grade Equipment

Threaded components and connectors used in demanding environments are sensitive to corrosion. Electroless nickel plating works to protect the threaded components.

For food processing and pharmaceutical equipment, electroless nickel plated to FDA-compliant standards provides the hygienic, corrosion-resistant surface that regulators require.

How EN-CHRO Plating Answers the Electroless Nickel Plating Call

EN-CHRO Plating runs both high-phosphorus and medium-phosphorus bath formulations, using the right chemistry based on the application environment and performance requirements.

Our tanks accommodate components of various sizes, from small precision components all the way up to pieces measuring 4 feet by 4 feet by 165 inches vertically. This means that long shafts and cylinders that need full-length coverage in a single bath pass, EN-CHRO set up can accommodate the various sizes.

The 750-degree Fahrenheit gas-fired walk-in oven handles post-plate heat treatment for parts that need even greater hardness. The oven handles components up to eight feet long, which keeps even large parts within reach of the heat treatment option.

For food processing and pharmaceutical customers, EN-CHRO’s processes comply with FDA regulations. That opens electroless nickel service to industries where coating compliance is mandatory. Our collective experience means we understand the documentation and process controls those customers need

You can review their full electroless nickel capabilities at enchro.com.

Choosing Between Hard Chrome and Electroless Nickel

The decision often comes down to three factors: part geometry, primary failure mode, and operating environment. The table below lays out the key technical differences side by side.

Part-by-Part Quick Reference for Heavy Machinery

Use this as a starting point when specifying a coating for a component.

What’s Next?

To learn more about which process is right for your application, contact EN-CHRO Plating today at quotes@enchro.com. We’ll help you through the process.