In this guide
Quick answer: cast iron is the better choice for abused, busy or exterior doors because it is rigid and absorbs punishment. Aluminum alloy bodies are lighter, easier to mount and fine for normal commercial doors.
Open a catalog and you will see "cast iron" used as shorthand for quality. That is largely fair, but it does not make aluminum bad. The best choice depends on the door and the frame.
Side-by-side comparison
| Cast iron | Aluminum alloy | |
|---|---|---|
| Strength | Very high, rigid | Good |
| Weight on door | Heavy, often 10 lbs or more | Lighter, often 5 to 8 lbs |
| Corrosion | Needs a good coating | Naturally resistant |
| Mounting | Needs solid backing | Easier on thin frames |
| Price | Higher | Lower |
Why installers like cast iron
A rigid casting keeps the piston and pinion aligned under load, which is what makes a closer feel smooth years later. It also gives the bolts something strong to pull against and copes better when somebody forces a door. That is why cast iron bodies are common on extra heavy duty door closers and on the older premium models people look to replace.
Where aluminum makes more sense
- Light frames, where a 12 lb closer would be a burden.
- Normal office and retail doors that do not get abused.
- Budget-sensitive jobs with a lot of doors.
Do not skip the finish
Bare cast iron rusts. A powder-coated cast iron body handles humidity and weather well, and it gives you the option of a black finish. If a closer sits outside or in a wash-down area, the coating and the cover matter as much as the metal.
The DRIWON options
The DN-9500 has a cast iron body with a wrought steel arm and weighs about 12 lbs. The DN-8220 is the lighter option at about 7 lbs. Both are Grade 1. Compare them in detail in heavy duty vs extra heavy duty.
See the cast iron DRIWON DN-9500 on Amazon →
Which body for which door?
| Door | Traffic | Our leaning |
|---|---|---|
| Office interior | Low to moderate | Aluminum alloy |
| Retail entrance | High | Either, Grade 1 |
| School main door | Very high | Cast iron |
| Warehouse man door | Moderate, rough use | Cast iron |
| Thin aluminum storefront | High | Lighter closer, frame-friendly |
| Exterior steel door in wind | Any | Cast iron |
Three myths about cast iron
"Cast iron closers last forever"
They last a long time, but the seals and the oil still have a finite life. A cast iron body will not save a closer from a blown seal. It just gives the internals a stiffer, more stable home.
"Aluminum closers are cheap junk"
Not true. Plenty of aluminum alloy closers are well made and carry high grades. Material alone does not set the grade. Testing does. A strong aluminum closer on a suitable door can outperform a poor iron one.
"Heavier always means better"
Weight can show a solid build, but it also puts more load on the fasteners and on the door. If the mounting surface is weak, a heavy closer can actually create problems. One buyer of the DN-9500 noted that its size and heavy screws could be too much for certain thin frames. That is an honest caution, and it applies to any closer of this type.
How to tell what you have now
If you are replacing a closer, a quick check will tell you what you are looking at. Tap the body: cast iron gives a dull, solid sound, while aluminum sounds lighter. A magnet will stick to iron and not to aluminum. Check under the cover too, since a label may give the model and grade. If the old closer was iron and lasted a long time, there is probably good reason to stay with iron.
Frequently asked questions
Is a cast iron door closer worth it?
Will a cast iron closer rust?
Are cast iron closers too heavy for wood doors?
← Back to Heavy Duty Door Closers