{"id":10698,"date":"2025-07-31T07:32:00","date_gmt":"2025-07-31T15:32:00","guid":{"rendered":"https:\/\/richconn.com\/?p=10698"},"modified":"2025-07-29T19:33:02","modified_gmt":"2025-07-30T03:33:02","slug":"hard-anodizing-vs-ordinary-anodizing","status":"publish","type":"post","link":"https:\/\/richconn.com\/hard-anodizing-vs-ordinary-anodizing\/","title":{"rendered":"Hard Anodizing vs Ordinary Anodizing in CNC Parts: Main Differences","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"\n

When you want CNC machined aluminum parts to look better and last longer, anodizing<\/a><\/strong>\u00a0is the top surface treatment; but not all anodizing is created equal. You can choose ordinary anodizing<\/strong>\u00a0(Type II) for a bright finish or hard anodizing<\/strong>\u00a0(Type III) for extra durability.\u00a0This choice depends on your project demand.<\/p>\n\n\n\n

In this blog post we will break down both processes and highlight the main differences so you can choose the right anodizing type for your next project.<\/p>\n\n\n\n

What is Ordinary Anodizing (Standard\/ Sulfuric Type II)?<\/h2>\n\n\n\n
\"What<\/figure>\n\n\n\n

Ordinary anodizing, or sulfuric Type II, uses an electrochemical process to increase the thickness of aluminum\u2019s oxide layer to about 1.8 to 25\u202f\u03bcm. It is done at room temperature, normally between 15 and 25\u202f\u00b0C.<\/p>\n\n\n\n

This technique gives the surface moderate hardness (mostly 150 to 250\u202fHV) and a porous finish. It has superb corrosion resistance and supports bright color dyeing. Therefore it is broadly used for decorating aluminum parts.<\/p>\n\n\n\n

What is Hard Anodizing (Type III \/ Hard Coat)?<\/h2>\n\n\n\n
\"What<\/figure>\n\n\n\n

Hard anodizing, also known as Type III or hard coat, forms a much thicker and tougher oxide layer on aluminum. It\u2019s done at cold temperatures and high voltage which results in a layer that\u2019s 13 to 150\u202f\u00b5m thick.<\/p>\n\n\n\n

The surface can reach hardness levels above 400\u202fHV\u00a0and sometimes up to 1000\u202fHV with the help of this anodizing. This dense layer gives aluminum extraordinary corrosion and wear resistance. Therefore it is perfect for demanding mechanical and industrial applications.<\/p>\n\n\n\n

10 Main Differences Between Ordinary & Hard Anodizing<\/h2>\n\n\n\n

We\u2019ve covered the basics of both anodizing methods. Now we\u2019ll look at the main differences between type II and type III anodizing.<\/p>\n\n\n\n

1. Coating Thickness<\/h3>\n\n\n\n

Ordinary anodizing, Type II, forms a thin layer. Its thickness is normally 1.8 to 25 micrometers (\u00b5m). Hard anodizing (Type III), on the other hand, forms a much thicker and stronger layer; and its thickness falls between 13 and 150 \u00b5m.<\/p>\n\n\n\n

2. Hardness and Density<\/h3>\n\n\n\n

A standard anodized surface is 150 to 250\u202fHV hard which is a basic protection. While hard anodizing has 300 to 600\u202fHV hardness and can go up to 1000\u202fHV. This hardness is as tough as many steels and makes CNC parts wear resistant.<\/p>\n\n\n\n

3. Voltage and Current Density<\/h3>\n\n\n\n

Final properties of the coating depend on the electrical settings. In any anodizing the oxide layer forms as a result of current density\u00a0applied during the process. Regular anodizing uses a lower current density<\/u><\/a>, mostly between 1.0 & 1.5 A\/dm\u00b2 and at 15 to 30 volts. While hard anodizing needs more electrical power. It uses 2 to 5.5 A\/dm\u00b2 and up to 100V to produce a thicker and tougher surface.<\/p>\n\n\n\n

4. Electrolyte and Temperature<\/h3>\n\n\n\n

Both processes use sulfuric acid as an electrolyte<\/u><\/a>\u00a0but at different temperatures. Standard anodizing is done at room temperature, usually at 15 to 25\u00b0C. This warmer environment forms a more porous layer. Hard anodizing, on the other hand, uses a much colder electrolyte, often below 5\u00b0C. The lower temperature slows down oxide dissolution and helps form a denser, harder coating.<\/p>\n\n\n\n

5. Wear and Abrasion Resistance<\/h3>\n\n\n\n

The difference in wear resistance is huge. Hard anodizing produces a surface that resists wear extremely well and can be even harder than case hardened steel. It is good for parts that are exposed to high friction or heavy industrial use.<\/p>\n\n\n\n

Unlike hard anodizing, regular anodizing only gives moderate protection from scratches and scuffs. Therefore it is good for decorative items or parts that don\u2019t experience too much mechanical wear.<\/p>\n\n\n\n

6. Corrosion Resistance<\/h3>\n\n\n\n

Both regular and hard anodizing increase corrosion resistance. Hard anodizing produces a denser and thicker coating which gives better protection. This is good for marine or industrial use. A high quality hard anodized layer can last over 336 hours in a salt spray test without showing corrosion.<\/p>\n\n\n\n

Regular anodizing protects general use parts well but relies on a sealing step to close surface pores and improve its defense.<\/p>\n\n\n\n

7. Porosity and Sealing Needs<\/h3>\n\n\n\n

Regular anodizing results in a surface with many pores which is good for dye absorption. But these pores need to be sealed \u2013 often with hot water or chemicals \u2013 to prevent corrosion.<\/p>\n\n\n\n

Hard anodizing, on the other hand, produces a layer that is much denser and less porous. To keep the surface as hard and wear resistant as possible this layer is usually left unsealed; and for extra lubricity, PTFE (Teflon) can be added to the surface.<\/p>\n\n\n\n

8. Dimensional and Surface Effects<\/h3>\n\n\n\n

The anodizing process causes the coating to grow both inward and outward from the aluminum\u2019s surface. Regular anodizing (Type II) adds 1.8 to 25\u202f\u00b5m thickness per layer with about half of that on each side. This results in little change to part size and keeps the surface smooth.<\/p>\n\n\n\n

Whereas, hard anodizing (Type III) produces much thicker layers i.e., up to 150\u202f\u00b5m and can make the surface 2 to 3 times rougher than bare metal. Plus, precision CNC parts need tighter dimensional control when using hard anodizing.<\/p>\n\n\n\n

9. Thermal and Electrical Properties<\/h3>\n\n\n\n

Anodizing creates an aluminum oxide layer which is an electrical insulator. Hard anodizing produces a thicker and tougher layer so it insulates better and can handle up to 2000V. This coating also conducts less heat as compared to bare aluminum which helps with heat control. Moreover hard anodized surfaces resist heat well and can survive brief exposure to 2000\u00b0C.<\/p>\n\n\n\n

10. Appearance and Costing<\/h3>\n\n\n\n

The two processes produce different looks. Ordinary anodizing is good for decorative purposes. It\u2019s porous so it can absorb a wide range of dyes and produce bright and varied colors. Also it is cheaper because it uses less power, requires a simpler setup as well as finishes faster.<\/p>\n\n\n\n

Unlike ordinary anodizing, hard anodizing produces a much thicker layer. This limits color choices so most parts end up with a black or dark gray finish. It is more expensive, often 1.5 to 2.5 times more as compared to standard anodizing. Longer processing, higher energy use and more complicated equipment drive up the cost.<\/p>\n\n\n\n

But for industrial applications, RICHCONN\u2019s streamlined process and bulk processing can help keep total costs down<\/em>;<\/em> <\/em>particularly<\/em> when you need consistent quality at high volume.<\/em><\/p>\n\n\n\n

Hard Anodizing vs Ordinary Anodizing: Uses<\/h2>\n\n\n\n
\"Anodized<\/figure>\n\n\n\n

Ordinary Anodizing<\/h3>\n\n\n\n

1. Consumer Electronics<\/em><\/h4>\n\n\n\n

Manufacturers use ordinary anodizing to give consumer electronics a premium look. Sturdy earbuds, colorful smartphone covers and slim laptop bodies often have this finish.<\/p>\n\n\n\n

2. Automotive (Non\u2010critical Aesthetic Parts)<\/em><\/h4>\n\n\n\n

Automakers use ordinary anodizing for non essential parts that need to look good. Custom gear knobs, interior trim and dashboard accents often have this process for a clean and stylish finish.<\/p>\n\n\n\n

3. Interior Design and Architecture<\/em><\/h4>\n\n\n\n

Architectural projects benefit from ordinary anodizing. It protects facade panels, window frames and door handles from weathering and at the same time provides a tough decorative surface in many colors.<\/p>\n\n\n\n

4. Packaging and Retail<\/em><\/h4>\n\n\n\n

Colored anodizing adds value to cosmetic containers, reusable bottles and branded aluminum packaging. These products stand out visually and get extra surface protection.<\/p>\n\n\n\n

5. Lighting and Furniture<\/em><\/h4>\n\n\n\n

Modern furniture and lighting products mostly use ordinary anodizing. Lamp housings, chair legs and other fixtures get an attractive and strong finish that suits modern designs.<\/p>\n\n\n\n

Hard Anodizing<\/h3>\n\n\n\n

Aerospace<\/em><\/h4>\n\n\n\n

Actuator housings, landing gear and valve blocks in aircraft get hard anodized coatings. These thick layers protect parts from corrosion and wear during harsh flight conditions.<\/p>\n\n\n\n

Medical Equipment<\/em><\/h4>\n\n\n\n

Surgical handles and housings for orthopedic tools need hard anodized layers. These can withstand repeated sterilization, cleaning and many years of clinical use.<\/p>\n\n\n\n

Defense and Firearms<\/em><\/h4>\n\n\n\n

Manufacturers apply hard coatings to optic mounts, trigger guards and weapon receivers. This gives the surface maximum scratch resistance and extends its life, even with frequent handling.<\/p>\n\n\n\n

Marine and Offshore<\/em><\/h4>\n\n\n\n

Underwater manifolds, propeller housings as well as marine hydraulic parts have hard anodizing on their surface. This coating resists saltwater corrosion and abrasion.<\/p>\n\n\n\n

Heavy Machinery and Industrial Automation<\/em><\/h4>\n\n\n\n

Pneumatic cylinders, robotic arms and wear guides use hard anodizing. This finish helps them withstand heavy loads, high friction and tough industrial conditions.<\/p>\n\n\n\n

Hard Anodizing vs Ordinary Anodizing: Pros and Cons<\/h2>\n\n\n\n
\"Red<\/figure>\n\n\n\n

Ordinary Anodizing (Type II)<\/h3>\n\n\n\n

Pros<\/em><\/h4>\n\n\n\n