Before chrome plating, it is very important to prepare the surfaces to be treated by machining them finely, because the result, in terms of chrome finishing to Ra 0.20 my, depends on the roughness of the surface before treatment. For this reason, it is necessary to hone the pipes before chrome plating, or grind and polish the stems.

The chrome thickness is important to make the plating strong enough for its design purpose. For example, the starting value may be 25my to then increase to 50my, 75my and 100my based on how heavy-duty the required application must be. The hardness obtained after surface chroming treatment is in the order of 850-950my HV0.3.

The welds can be located in one or more points along the pipe, and as whole will form the liner of the hydraulic cylinder. However, if pipe welding is not adequately designed into the scope of a forward-looking project, it will inevitably cause detectable deformation in the pipes, resulting in the piston locking during linear movement, damaging the gasket and affecting its operation.

To solve this problem, our programming includes, during the production cycle of each component, a honing cycle after welding, in order to “readjust the balance” of the mentioned deformation and restore the desired geometry, which guarantees optimal sliding of the piston inside the liner.

This operation technically involves several steps: from roughing to finishing. Basically, and intuitively, in the first steps the cutter is programmed to quickly remove a significant amount of material.

Towards the end of the process, machining is fine tuned to focus on accuracy: the residual stock is removed to achieve the best compliance with the desired result, in terms of both dimensions/tolerances and surface roughness.

Among the most important parameters, in addition of course to strict compliance with expected results, there are also cutting speed in line with the hardness of the material, and tool feeding rate according to the density of the material, for an optimal result.

In particular, the production of components such as liners for hydraulic cylinders requires a production cycle that includes a sequence of phases to be strictly observed, in order to guarantee machining quality.

For example, welding, when required by the circumstances, must necessarily be carried out before honing, to avoid any deformation, while turning is performed before welding to prepare the workpieces and then finish them.

Additionally, when geometric tolerances ensuring tight concentricity and perpendicularity with respect to the honed hole are required, then it is necessary to design a production cycle including reworking through final turning.

Scheduled cylinder maintenance: One or more annual checks must be programmed in advance based on the hours of operation; if, upon visual inspection, any leaks or unusual wear are found (e.g. stem scratches), action will be taken accordingly.
Proper routine maintenance extends the service life of the cylinder and helps ensure a high standard of operation.

Unscheduled cylinder maintenance: Urgent action required after sudden, unpredictable failures.
If unscheduled maintenance is required, it is necessary to rely on skilled industry specialists as this is a very delicate process that requires specific know-how and extra care.

Skiving-rollerburnishing is performed on EN10305 tubes with suitable stock allowance, generally -0.5-0.7 mm, and features a higher productivity than honing; for this reason skiving-rollerburnishing is performed on standard bars available commercially.

This solution makes it possible to create good value, functional cylinders as long as no welds are required that are likely to deform the tube and affect smooth piston sliding.

Our production process includes a first preparatory phase which consists in aligning the workpiece on the lathe; this phase is very important because it determines the quality of final machining which must be as concentric as possible with respect to the outside.

The importance of this operation should not be underestimated because hot rolled tubes, manufactured according to EN10297, have wide dimensional tolerance specifications for the outside diameter and thickness and for this reason, the desired bored diameter cannot be always obtained.

In this phase the unmachined tube sag is measured and if it exceeds a certain value, additional straightening on the hydraulic press is carried out.

The inspections carried out after machining completion are: visual inspection to detect any defects inside the tube, such as holes due to lack of material and instrumental testing using a micrometer, to both check the inside diameter dimension and measure the thickness of the tube at both ends, so as to determine the eccentricity tolerance between the inside and outside of the tube.

Additionally, our production process allows a workpiece to be obtained ready to be subsequently tailstock machined with external turning, guaranteeing a high degree of concentricity between the inside and outside diameter of the tube.

Internally honed tubes are available commercially as standard products, but it is not uncommon for certain limit conditions to occur which require non-standard products: special diameters, high thicknesses, steels other than standard.

One of the typical features of our machining process is our focus on every detail of customer projects – to achieve the best possible honing result. As proud specialists, we are able to start from mechanical piping to perform, in addition to other processes, honing to such a high precision degree that the best surface concentricity and perpendicularity can be guaranteed to even exceed cylinder pressure test requirements.