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Proper assembly of the sealing elements in the hydraulic cylinder. It is very important for its performance and service life. During assembly, assembly tools with sharp edges should not be used. Impropriety that may occur during installation may damage sealing elements. As a result of these improprieties damages can occur and these damages can not seen visually becuase of the sealing elements will remain in the cylinder after assembly. So, in a short time, leakage, prudent work, no movement on cylinder problems can observed and these problems can lead to such as damage to the hardware.

Cleanliness of Assembly Area
Clean area for installation is important during assembly. Before assembly, cleanliness of the assembly tools and assembly table should be checked and get suitable for installation. Small strange particles can stick to sealing elements from the nonsuitable area and these particles can cause to serious problems over time. Contamination of hydraulic fluid may cause deformation of seals. Also scratches are possible on rod and bore and deformed, leak in cylinders, faults can occur on valves and pumps.

Check in Cylinder and Sealing Elements
Products must kept in their packaging until the moment of assembly and should open during assembly and it must be checked is there any deformation seals have due to storage, packaging etc. In addition, the surface of the bore, rod and product grooves in the cylinder should be checked and attention should be paid to the bore, rod chamfer dimensions. Make sure that there are no burrs and sharp edges on metal parts. Auxiliary apparatus should be used to protect the products to be passed over the teeth from the notch effect.

Check List
If seal that will install the cylinder has more than two parts, (for

example PTFE with o-ring, PU with NBR parts, packings, compact set, etc), make sure seal set has not missing or wrong dimension part. During the replace of sealing elements they must be replaced all together, because it is considered all sealing elements that working together worn at the same time. The main seal replacement will not be enough.

Lubrication
Lubrication of the sealing elements during assembly help to reduce friction forces and ensure to easy assembly. Care should be taken to use suitable fluid and suitable assembly greases in the system.

Heating
It will be helpful by keeping the product in hot oil or hot water (80-90° C) for five minutes to increase flexibility of seal which have high material hardness (PTFE, 50 Shore D and above Thermoplastics, etc.) and with high cross section. Thus, assembly can be realized with lower forces and the risk of plastic deformations that may occur in products can be eliminated.

Preforming
Preforming proces can ensure easier assembly for especially guide rings and back-up rings which are produced from hard thermoplastics with high compression set value (such as PTFE) The guide bands can assemble on rod and can be kept, therefore they can take shape of rod ensure with circularity. Fast and proper assembly can ralized with preforming for the products which have big diameter and small cross section.

Bleeding of Hydraulic Cylinder
Air in the hydraulic cylinders can cause big problems. The problems such as diesel effect, jet cutting effectcan occur and can damage seals and metal surfaces seriously. Always bleeding process should made after cylinder seal assembly and than cylinders should be assemblied on the system.

Seal Cross Section Values for Installation to Closed Grooves

When selection of seals, especially if they are to be installed in closed grooves, values such as wall thickness, diameter and material should be considered; otherwise, the products may not be installed.

  ≥ 94 Shore A < 94 Shore A ≥ 94 Shore A ≥ 94 Shore A
4.5 25 44 44 69
9.5 76 127 152 203
20 203 228 381 431

* Example: Cross section=d:100 xD:112XH:8 such as K33 rod sea=(112-100)/2=6l

* If the seal dimensions over than recommended these values, groove of the sealing element must be designed in accordance with the open groove.

Piston Assembly Tools

EXPLANATION

  • If a "K17" type sealing element is used, first, the o-ring or elastomer energizer installed the groove ring is checked for twisting in it’s groove product groove.
  • O-ring sould be checked if there is any twisting on it.
  • Conical apparatus is fitted to the piston head.
  • Conical apparatus and PTFE ring should be lubricated and than PTFE ring is fitted to the piston head.
  • PTFE ring can be pushed with slotted apparatus by hand or geared head drilling therefore PTFE ring can be stretched and fitted to it’s groove on o-ring.
  • After installation of «PTFE ring and o-ring», guide rings can be installed to piston head and piston head is ready to install cylinder bore.
  • Completed piston head can be installed with conical female apparatus to cylinder bore that can see below Picture 3.24.

ADVANTAGES
In assembly process, the sealing element can be stretched properly all around on diameter when slotted and conical aparatus are used. Thus, it can be reduced these possibilities; deformation of product caused by stretching in one direction, break caused by plastic deformation, and issue of issue of stretched seal without apparatus therefore it can not be back to its first position if too much force is apllied to seal. It allows very fast and correct installation.Apparatus can be used for a long time. In case of thread on the bore, an extension should made on conical female apparatus. Thus, with this extended female apparatus, stretched seal can be shaped properly on all around and notch damages can be prevented caused by thread during assembly to bore. Proper chamfer dimensions can not produced on thin walll thickness bore.

In this type of bores, the usage of conical mouth apparatus have importance to prevent damage to the sealing elements and ensure safe assembly.

NOTES

Apparatus materials can be manufactured from POM material. The conical apparatus "L" length should be determined to fit the PTFE ring groove according to the length of the piston head to be mounted. O-ring groove can designed on the slotted apparatus and therefore the o-ring help to flexibility of apparatus.

Alternative PTFE Ring İnstallaton to Piston

Piston seals which made out of PTFE, thermoplastic elastomer and elastomer materialsİf there is no possibility to use apparatus in the assemblya ribbon or high tensile strength fabric with a slippery surface can be used for stretching.

If PTFE piston seal with energizer ring will be used, first, elastomer parts (o-ring, etc.) must install it’s groove and it is checked is there any twisting on o-ring. First guide rings must be installed to piston and then installation of PTFE ring should be started.

After the PTFE ring heating is done (PTFE ring should kept in about 80-90 °C water or oil for 5 minutes) about 120 degrees of seal can be fitted it’s groove. Then the ribbons pass into a PTFE ring as seen in picture 3.27 and force canbe applied one direction with controlled stretching at the same time rotational movement is done with ribbons. Lubrication with compatible oil of the seal can make installaton process easier.

Compact Piston Seal Installation

If a compact set will use, firstly, the elastomer (rubber) part assembly with the help of conical apparatus or alternative installation (with ribbon) performed. Then the above TPE and POM parts respectively Installation of the piston head by ensuring flexing as seen performed. For compact seal assembly stretching of hard plastic products in their perpendicular axis and must be careful about this detail. Otherwise horizontal stretching, can casue to such as deformation, breaking and non suitable shape problems can be seen.

Note: Especially for compact seals which have large diameter sizes (Ø100 and above) and thin cross-section, compact set is recommended to be preferred that have glass fiber-reinforced thermoplastic guide rings.
(For example: K518-K518X)

Rod Seal Assembly

In the assembly of the rod seals, shown in Picture 3.31 apparatus can make assembly fast and easy. Rod sealing element fit to the apparatus as in step 1 attached. After, the red levers are rotated in the direction of the arrow and geometric form is realized in step 2, on step 3 approximately 180° area of rod seal fit into Groove and the red levers are gently loosening in the opposite direction so instalattion is completed. Seals must be installed with the most suitable levers apparatus according to the their diameters. Values according to diameter and cross section that are given in Table 3.2 must be considered for selection of products and than installation to be realized.

PTFE Rod Seal Installation with Slotted Apparatus

Rod seal installation can be done with help of conical slotted apparatus which made of POM or PA material,especciallly it is hard to reach by hand which have deep groove, also small diameter (<Ø40 mm) (Ø<40 mm).

The slotted conical apparatus can be produced with angle of 7-10° which should be made 5-10% larger than PTFE ring diameter.

“L” dimension length on apparatus should be extended up to seal groove line. Slotted apparatus and conical apparatus can be used for rod seal installation as seen below picture. The rod seal can be slided inside conical appartus wih the help of slotted part, therefore equal force can be apllied all around on seal ring and suitable installation can be ralized.

PTFE Rod Seal Installation Without Tool

Elastomer energizer ring (o-ring etc.) is fitted in the groove first and it is checked for is there any twist on ring. PTFE ring's form is changed with applying hand force blue arrow direction seen Picture 3.35.

The PTFE ring that is given form can fitted into groove about 180° and than opposite direction force can apply to ring by finger as seen picture 3.37.

When changing the form of PTFE ring it must pay attention to flexion section is not be on notch. With the aim of the PTFE ring's return to it's first positon conical male apparatus that have good surface can be used with press force inside the ring and rotational movement is done inside of the ring. Before the cylinder rod installation it must be checked is there any deformation inside surface of PTFE ring.

Packing Installation

Packing Height Adjustment
The shims have an important effect on packing applications. (If the temperature that on the rod increases during operation, must be pay attention) When the temperature increases, the number of shimes shown in the above figure is increased to reduce packing preload.
of preload shimes and leakage can be prevented. Over time, there

may be preload losses in packing elements that working under pressure. In this case pre load can be increased by removing shimes from between packing. It is recommended to install with plastic and non-sharp corner pushers which have yellow color seen in Picture 3.40 and Picture 3.41.
When seal is pushed inside of bore with the thick pusher seal and force is applied to seal every 60° all around at the same time thinner pusher helps to seal lip for mounting to bore.

Packings up to Ø400 mm inner diameter can be installed without cutting. However, they can be assembled by cutting 45° on Ø400 mm diameter, if it is necessary. It is recommended to use a sharp knife when cutting process and the above auxiliary plastic apparatuses should be used for mounting. Cutted surface must be checked is there any fluufs or small particles.

If cutting is required before installation «K» gap must be checked for zero value. It is important to mounting parts by adjusting the cutted surface 120° angle on installation.

Above; as shown in Picture 3.45, if packing seals assembled to open groove without rod, fitting problems may occur. With this type installation, packing parts can be squeezed on unsuitable position. Therefore, surface abrasions and system temperature can increase. The parts must be assembled one by one into groove and it paid attention to fitting concentric.

Spring Energized PTFE Seal Installation

Installation to Closed Groove
Value specified as Ød1 dimension can be calculated, according to groove cross section. The products which have small diameter and big cross section. It may not be possible to install into closed groove. It is recommmended to use of closed grooves for rod and bore that have bigger diameter than 50 mm. Calculation of Ød1 for rod application it is equal to (ØD-E/2), for piston applications Ød1 should be calculated as (Ød+E/2).

It is recommended for maximum 4% difference of Ød1 value from groove diameters For example: If ØD: 50 mm then Ød1: 48 mm (min) should be. Please contact the sales department about detailed information and technical drawing of closed groove installation.

It is recommended to installation of spring energized PTFE seals into open groove. If it needs for installation into closed groove, it is paid attention to proper Groove and dimensions as shown Picture 3.47. Care should be taken against scratches in spring PTFE products.It should not be forgotten of PTFE material can damaged easily. First, PTFE seal is fitted to chamfer by hand and too much force is not applied to seal and than seal pressed with the help of conical male apparatus. It is paid attention for proper installation without damage to seal. Also it is paid attention to after the installation, make sure about PTFE is not damaged and spring is correct position in PTFE seal. It is recommended to install to open groove, for thick cross section products and rotary applicaton seals. Also this situation may be required depending on product design. Please contact the sales department about detailed information and technical drawing of open groove installation.

 
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