Talking balls

Why the Labelling Confusion?

In short, the terms "chrome steel" and "carbon steel" are often misused in the pinball industry in an effort to simplify the delineation between the 2 types for the consumer:

"Chrome Steel"

This term is used for 52100 steel because of its chromium content, but it’s not chrome-plated (plating flakes off and damages playfields). The shiny appearance reinforces the "chrome" label. These are high-carbon, chromium-alloyed steels. MAYA brand chrome steel pinballs are a particularly durable 52100 type.

"Carbon Steel"

Some sellers advertise these as "carbon steel" to distinguish them from shinier "chrome steel". Think shiny chrome vs satin graphite. This is often used to describe case-hardened low-carbon steel balls marketed for magnetisation resistance. The term is a misnomer on 2 levels:

1. All steel contains carbon. Carbon is the primary alloying element that differentiates steel from raw iron.
2. In this context, it implies a low carbon content to reduce magnetic retention.
   

Marketing and Tradition:

Pinball suppliers may use these terms to differentiate products for games with magnets (low-carbon) vs. those without (chrome). However, at MAYA Pinball we believe this over simplification has lead to more confusion than necessary. We suggest that you always start off trying to use chrome 52100 pinballs for games both with and without magnets because they are simply better than the case hardened low-carbon varieties. Chrome steel pinballs are harder, are inherently more corrosion resistant, and have a better surface finish, which also lasts longer. A better surface finish places less wear on all the other components of the pinball machine and this is why pinballs should be inspected and replaced when worn. This is why our boxes of chrome steel pinballs are marked as "suitable for games with and without magnets". If you experience issues such as trough jamming or ramp sticking in games with magnets after extended play, first check the trough or ramps for dimples or low spots and remedy this first before immediately jumping to switch ball metallurgy. A lightly magnetised ball can sometimes lead an area of mechanical wear to reveal itself.

Of course, some games (particularly those that hold the ball with exposed magnet cores, or which grab the ball in the bore of an electromagnet) can more rapidly magnetise balls than others. This can quickly lead to infuriating issues with magnetisation, such as stuck balls in otherwise mechanically sound mechanisms, or ball adhesion in multiball sequences. If this happens to the point where the effort or frequency of degaussing becomes a frustration, then of course, see how you get on with the low-carbon "carbon" magnetisation-resistant varieties of balls from other manufacturers. These should last longer from a degaussed state to the point where play issues arise. We want everyone to get the maximum enjoyment from pinball, so see what works.

Magnetic vs. Magnetic Retention: Understanding the Critical Difference

A common misconception is that "magnetisation-resistant" balls are non-magnetic. This is incorrect. Both chrome steel and low-carbon steel pinballs are ferromagnetic, meaning they're strongly attracted to magnets during play. The crucial difference lies in magnetic retention after the external field is removed. When a pinball passes through a magnetic field (like an under-playfield magnet or electromagnet), it temporarily aligns its internal magnetic domains with that field. In chrome steel, the high carbon content creates numerous carbide particles that act as "pinning sites", microscopic anchors that lock these magnetic domains in their aligned state even after the ball leaves the magnetic field.

This is why a chrome steel ball can retain enough residual magnetism to stick to metal surfaces or interfere with trough sensors hours after exposure. Low-carbon steel, with fewer carbide pinning sites, allows its magnetic domains to more easily randomise once the external field is removed, though this process isn't instantaneous. Both ball types will still be attracted to active magnets with equal force during gameplay. The difference only becomes apparent in how long they "remember" that magnetic exposure afterwards. This is why degaussing (applying an alternating magnetic field, or sharp impact to scramble the domains) works on both materials, but chrome steel balls typically need more frequent treatment in games where this can cause issues.

Clarifying the Terminology and Materials

1. Standard Pinballs ("Chrome Steel"):
   • Material: Most standard pinballs are labelled as "chrome steel," but this typically refers to AISI 52100 steel, a high-carbon, chromium-alloyed bearing steel. This is not "chrome-plated" but rather a steel alloy with chromium for enhanced hardness and wear resistance.
   • Magnetic Properties: 52100 steel is ferromagnetic. It can become permanently magnetised when exposed to magnetic fields (e.g. in pinball machines with magnets), causing issues like sticking in troughs or on ramps.
   • Lustre: These pinballs are often highly polished to a mirror finish, giving them a bright, shiny appearance out of the box. The chromium content and fine polishing contribute to this lustre.
   • Metallurgy: 52100 steel is through-hardened, meaning the hardness extends throughout the ball, making it more durable.
2. Magnetisation-Resistant balls ("Carbon Steel"):
   • Material: Pinballs labelled as "carbon steel" for magnetisation resistance are often case-hardened low-carbon steel (e.g., AISI 1010 or 1020).
   • Magnetic Properties: These have a soft core with a hardened surface. They are ferromagnetic but have lower magnetic permeability than 52100 steel due to less carbon alloying, making them less prone to retaining permanent magnetism
   • Lustre: These pinballs often have a satin or less lustrous finish compared to 52100 chrome steel. Low-carbon steel balls may not be polished to the same mirror-like sheen, often described as having a "satin finish" compared to the "ultra shine" of chrome steel.
   • Metallurgy: Low-carbon steel is case-hardened for surface durability but softer overall, leading to shorter service life. 

Why is Chrome Steel Easier to Polish?

"Chrome" steel (AISI 52100) is easier to polish than low-carbon steel (AISI 1010/1020) due to its metallurgical properties:

1. Higher Hardness and Uniform Structure:
   • AISI 52100 is through-hardened to 60–66 HRC, creating a uniform, fine-grained martensitic microstructure. This hardness and consistency allow for a smoother, more reflective surface when polished, achieving a mirror finish.
   • Low-carbon steel is case-hardened, with a softer core . The softer core and variable hardness make it prone to micro-abrasions or uneven polishing, resulting in a satin finish.
2. Chromium’s Effect:
   • Chromium (1.3–1.6% in 52100) enhances surface smoothness by forming fine chromium carbides that improve wear resistance and polishability. These carbides create a more uniform surface texture during grinding and polishing.
   • Low-carbon steel has negligible chromium (0–0.2%), lacking these carbides, so its surface is less receptive to high-gloss polishing and scratches more easily.
3. Polishing Process:
   • Chrome steel’s higher hardness allows manufacturers to use aggressive polishing techniques (e.g., multi-stage tumbling with fine abrasives) to achieve a low RA. The material’s resistance to deformation ensures a consistent, lustrous finish.
   • Low-carbon steel’s softer core limits aggressive polishing, as it may deform or develop surface irregularities, leading to a less reflective satin finish.

Why Isn’t Chromium Added to Low-Carbon Steel Pinballs?

Low-carbon steel pinballs are used in magnet-heavy pinball machines because their lower alloy content results in lower magnetic permeability. Adding chromium (as in 52100) increases magnetic permeability by stabilising ferromagnetic structures, making the balls more prone to retaining magnetism, which defeats their purpose in magnetisation-resistant applications.

Why does MAYA vacuum pack pinballs inside the external packaging?

Through our research and testing we found it is particularly important to keep pinballs away from cardboard during storage and transportation. This is why we go to the extra step of vacuum sealing our pinballs inside of the outer packaging. Not only does this prevent the balls from impacting one another during transportation, but also mitigates other issues of cardboard storage:

• Moisture Retention: Cardboard can absorb and retain moisture, especially in humid environments (during shipping or storage). If pinballs are stored in direct contact with cardboard, this trapped moisture can accelerate corrosion.
• Acidic Content: Some cardboard contains acidic compounds (e.g., from manufacturing processes or recycled materials) that can react with steel surfaces, promoting corrosion over time.
• Abrasion: Cardboard may cause micro-abrasions during handling, exposing bare steel to air and moisture. 
• Inhibitor Loss: Cardboard can absorb inhibitors on the ball surface designed to keep the balls in perfect condition while in storage. This should only be wiped off at the point of installation. 

Balls that arrive factory-fresh get to enjoy a long service life in games. We're confident you'll appreciate just how long MAYA pinballs stay looking great in your games!