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bmdr · 04-06-2025, **(Subject: X15 LINER FINISH )**

HELLO GUYS
HAS ANY SEEN A BRAND NEW OEM X15 LINER WITH A FINISH LIKE THIS?
LOOKS LIKE IT HAD BEEN THROUGH SOME KIND OF BLAST PROCESS THEN HONED. ALL SIX APPEAR LIKE THIS, I DON'T RECALL SEEING THIS IN THE PAST.

Rawze · 04-07-2025, **(Subject: X15 LINER FINISH )**

Its not a blast process, but a deposition process ... depositing hardened chromium in a thick layer onto the surface of the initial casting ... then honed back down to create the cross-hatching, and to meet the dimensional tolerances.

Looks perfectly fine to me. All the cross-hatching and roughness is on purpose to trap oil and reduce/minimize friction.

Too smooth = no place for oil to get trapped between the surfaces+ more contact surface making more resistance, and too rough = accelerated wear of the piston rings due to a 'sand-paper' type of effect.

bmdr · 04-14-2025, **(Subject: X15 LINER FINISH )**

(04-07-2025 )Rawze Wrote: Its not a blast process, but a deposition process ... depositing hardened chromium in a thick layer onto the surface of the initial casting ... then honed back down to create the cross-hatching, and to meet the dimensional tolerances.

Looks perfectly fine to me. All the cross-hatching and roughness is on purpose to trap oil and reduce/minimize friction.

Too smooth = no place for oil to get trapped between the surfaces+ more contact surface making more resistance, and too rough = accelerated wear of the piston rings due to a 'sand-paper' type of effect.

Thanks for the reply! That's WAY more information my local Cummins distributor would give out. Was more less told to trust (its fine). Its a shame even after being fully Cummins certified in light, medium and heavy that this kinda of question cant be answered when asked Cummins at the dealer level. I'm a very thirsty for knowledge even after 30 years in service at a dealer, and even more so being have started my own business specializing in engine work. thanks again for the response which make perfect sense to me now.

Rawze · 04-15-2025, **(Subject: X15 LINER FINISH )**

(04-14-2025 )bmdr Wrote:
(04-07-2025 )Rawze Wrote: Its not a blast process, but a deposition process ... depositing hardened chromium in a thick layer onto the surface of the initial casting ... then honed back down to create the cross-hatching, and to meet the dimensional tolerances.

Looks perfectly fine to me. All the cross-hatching and roughness is on purpose to trap oil and reduce/minimize friction.

Too smooth = no place for oil to get trapped between the surfaces+ more contact surface making more resistance, and too rough = accelerated wear of the piston rings due to a 'sand-paper' type of effect.

Thanks for the reply! That's WAY more information my local Cummins distributor would give out. Was more less told to trust (its fine). Its a shame even after being fully Cummins certified in light, medium and heavy that this kinda of question cant be answered when asked Cummins at the dealer level. I'm a very thirsty for knowledge even after 30 years in service at a dealer, and even more so being have started my own business specializing in engine work. thanks again for the response which make perfect sense to me now.

There is an entire science behind optimizing roughness, roughness patterns, etc. between making surfaces that have to rub against each other along an oil film with the least resistance and wear over time. At one point in my corporate past (pre retirement), I had some classes on this, but they were only the basic principles. Its a shame how much those 'official' training sessions of today somehow omit damn near everything important.