Case Study: Engine Inlet Cowl Polishing

Aerospace Surface Prep · Polishing · Case Study

Engine Inlet Cowl Polishing: 36 Hours Down to an Estimated 8

GKN Aerospace replaced a long grit progression and a paste polish with a shorter Mirka sequence. A faster process, with a better finished appearance in the customer-provided photos.

  • 36 hrsOriginal process
  • 8 hrsEstimated Mirka process
  • 78%Less estimated time
See the Process Shop the Products Used
Side by side

Two Ways to Polish One Engine Inlet Cowl

The legacy sequence ran the full grit range, then a separate oil and paste polishing step. The Mirka sequence starts coarser, drops the oil step, and finishes with a wool pad and Polarshine 10.

Sanding discs laid out on the bench, customer-provided photo of the abrasive progression
Original process

36 hours per cowl

Total process time, customer reported
  1. Sand from 180 grit through 4000 grit
  2. Apply kangaroo oil
  3. Polish with Mothers Aluminum Polishing Paste
Polarshine compound bottles beside the mirror-finished inlet cowl, customer-provided photo
Mirka process

8 hours estimated per cowl

Calculated estimated completion time
  1. Sand from 240 grit through 4000 grit
  2. Polish with a yellow wool pad
  3. Finish with Polarshine 10 (PC-10)

Shorter sanding progression, simpler final polish, and a more uniform reflective finish in the customer-provided photos.

Customer impact

Faster process. Better finished appearance.

For GKN Aerospace, the Mirka process creates a meaningful productivity improvement on each engine inlet cowl. The customer saves time and labor while achieving a better finished appearance.

  • Original process36 hours
    36
  • Mirka process (estimated)8 hours
    8
  • Scale: 40 hours maximum
28hours saved per cowl
78%less estimated process time
Customer-provided photos

The Finished Cowl

Technician seated beside the polished engine inlet cowl, the mirror finish reflecting the shop
Finished inlet cowl after the Mirka sequence.
Polarshine 10, 8 and 5 bottles on the bench beside the polished cowl
Polarshine compounds on the bench during the final polish.
Shop the process

The Products Behind the 8-Hour Sequence

GALAXY grip discs cover 40 through 2000 grit. Abralon carries the sequence to P4000. Then a yellow wool pad and Polarshine 10. Every grit on one page, with one Add to Cart.

Mirka GALAXY grip sanding disc
Step 1 · Sand

GALAXY Grip Discs, 3" to 8"

Grits 40 to 2000 · from $23.78 / 50
 Mirka Abralon 6 inch grip disc
Step 1 · Fine sand

ABRALON 6" Grip Discs

P180 to P4000 · $74.42
 Mirka 7.5 inch yellow twisted wool pad
Step 2 · Polish

7.5" Yellow Twisted Wool Pad

$21.58 each
 Mirka Polarshine 10 polishing compound, 1 liter
Step 3 · Finish

Polarshine 10 Polishing Compound

250 mL, 1 L, 5 L · from $34.78

See the Full Polishing Lineup

Source. Customer-provided process details and photos supplied for this case study. The 8-hour figure is a calculated estimated completion time per cowl. 36 - 8 = 28 hours saved; 28 / 36 = 77.8%, rounded to 78%.

Polishing a Part Like This?

Tell us the alloy, the starting surface and the finish you need. We will lay out the grit sequence, pad and compound, and build the stocking plan behind it.

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