surface finish for hydraulic cylinder

[Anonymous]

i am currently designing a minature hydraulic damper and this is the first time i have ventured into this field and I am having trouble specifying the surface finish for the cylinder. can anyone point me in the right direction
tia
nigel

[Anonymous]

You definately have an engineering question here.

www.eng-tips.com and search for finishes. The seal manufacturer should be telling you that.

[Anonymous]

Standard hydraulic cylinder bores run 8-12 RMS though the seal people are now specifying finishes in terms of Rz, Rmax. This holds for 'normal' size bores (2" to 12" ) - for tiny stuff, I'm sure 'sticktion' become more of an issue.

[Anonymous]

Airpot makes "friction free" small cylinders. Check them out.
Gary

[Anonymous · Accepted solution]

Normally the surface of the hydraulic cylinder tubes is honed finish or skiving & roller burnishing finish. The surface is bright and very smooth, usually with surface roughness Ra < 0.4 microns. 

The surface of honing finish is cross-grain, which is beneficial to the storage of lubricating oil and the maintenance of oil film. Under this consideration, engineers may choose surface hydraulic cylinder tubes in honing finish.

And for cylinder tubes with skiving & roller burnishing finish, as through Roller burnish forming, the rolling surface forms a cold hardening layer, which reduces the elastic and plastic deformation of the grinding contact surface, thereby improving the wear resistance of the inner wall of the honing pipe and avoiding burns caused by grinding.

You can know more about honing surface & Skiving & roller burnish surface in below website

https://skylinepipes.com/articles-news/advantages-of-honing-vs-skiving-roller-burnishing-process/

In one word, the surface finish you choose is determined by the performance of the hydraulic cylinder you want to achieve. 

[leoolee]

It seems you are talking about the inner surface finish of the hydraulic cylinder barrel, yes, it is true that the hydraulic cylinder barrel is mostly with inner surface of max. Ra0.4 microns, extremely smoothy right?  This is because the hydraulic cylinder barrel is made of honed tube that is a kind of cold draw seamless tube or DOM tube with honing on inner diameter.

However, besides the hydraulic cylinder barrel, there are also other parts such as the cylinder rod, cylinder, seals and so on. What is the surface finish of these parts? What is the surface finish of the outer surface? That is really a complex question. Anyway, we can see normally the hydraulic cylinders are with outer surface finish of painting.

[johnsonshiue]

Hi! If you are interested in surface finishing appearance, you may want to sign up Inventor Feedback Community (https://autode.sk/InventorBeta). This happens to be an area we are working on. You may try the workflow on the latest internal build and give your feedback to the project teams.

Many thanks!