Water jackets cleaning

One of the more difficult areas to clean in the cylinder heads and cylinder blocks of the automobile engines is the water jackets,Why?

1) The internal volumes of the water jackets are complex and very often with narrow passages. By one side the cylinder head designers wants to have a minimum water jacket volume in order that the engine can rise in temperature rapidly to have the optimum engine performance. By other side is important to refrigerate all the areas of the cylinder head , mainly around the combustion chambers , but the number of valves per cylinder create narrow passages inside the water jackets.

2) On the machining of the aluminium alloys the cutting speed are more and more elevate and create longs chips . The cycles times on the machines are more and more shorts and there is not too much time to break the chips.On the transfer lines it was easier to do than in the present CNC flexible lines.

3)As consequence of the cutting speeds and short cycle times the chips are very often pushed inside the water jackets by the final milling tools.

4) The consequence of long spring chips inside small pockets and narrow passages  is chips trapped inside the water jackets.

The cylinder head is more sensitive to this problem but some cylinder block too. Here joint you can see what you can find inside a cylinder head water jacket:

       There is a clear test : If we cut a supposed clean cylinder head in slices it will allows us to see if there are some chips trapped inside the water jacket. I’ll say that the majority of clean cylinder heads have chips inside.

Is dangerous for the engine run? Well, first you have to assembly your engine (cylinder head , cylinder block , camshafts, crankshaft..). During the automatic assemply this remaining chips can fall down of the parts and goes to the assembly machine or between the parts to be assembled blocking the operation and stopping the machine and the line.

Second if you assembly your engine with no problem but the chip remain inside , is possible than during the engine run with the vibrations and , temperature changes , the chips goes out of the water chamber and arrives to the water pump causing the failure of the water pump , heating the engine and stopping the car engine.

Another added problem is the remaining sand balls remaining inside the water jackets coming from the cast process:

 

 

 

Since many years this water jacket problem has been the major nightmare for the equipment suppliers and for the automotive industry .

The process to remove the remaining sand inside the water jackets  is called “desandind” and will be considered in a further post . today we will concentrate only in the chips removal :

Some suppliers were using a contact jet at 20/30 bars to flush inside the water jackets( ICOM, Hafroy). Or” injection flood” ( Dürr) injecting 10/15 bars jet against the waster jacket on immersion of the part . Or the “Aqua cannon”(Valiant) with a medium pressure short discharge inside the part pulsing the water inside. 

Or the High pressure ( 200 bars) target injection trough the part openings (Agullo).

Or a mixture of systems like Sugino .

In any case the problem is a difficult problem and needs test with real parts to achieve an acceptable process. Of course the automobile client is also an important part. If the cleanliness test to control the cleanliness of the cylinder head is a manual flushing of a solvent trough the part( and water jacket ) is probably than the flushing (normally at 1 to 3 bars) will not be able to remove the blocked chips inside the water jackets and the test can give a result of accepted clean part when it has trapped chips inside the water jackets.

Some cleanliness tests in the automobile have added operations to the cleanliness test procedure to verify these water jackets. One is the manual hammer percussion by the operator of the cylinder head in a certain position in order to detach the chips balls inside . I remember than years ago in an european engine manufacturer the company Hafroy supplied one transfer machine that had a pneumatic hammer in one of the Ferris wheel wash stations to reproduce the operator cleanliness test operation and try to remove this balls. I remember that the line operators call the machine the “Bell” ( a “dong” each 30 secs was not appreciated by the operators around the line).

Another system is the manual checking of the water jackets with a small  endoscope . This system is of course the more efficient but some times you can not reach all the internal areas. Only cutting the cylinder head you can really check it.

To reduce the chips and traps inside the water jackets is necessary a close work between the cylinder head designers ,cylinder head  machining engineers and the “cleaning” engineers to avoid narrow passages inside the water jackets design , to avoid big and spring chips during the machining, to have high coolant volume during the machining , or cover plates during machining . If you diminish the size of the chips , if you avoid the spring chips , if you avoid narrow passages and traps inside the water jacket , if you have more than one opening of the cylinder head water chambers you will have more opportunities to remove the inside trapped chips.

Maybe one of the Automobile manufacturers that pay more attention to the water jackets has been Fiat . In their wash process specification the request several water jacket wash operations in each of the washers of the cylinder head line. More water jacket wash operation you have with the part in different positions and injecting the water by different areas to create different flows inside the water jackets allows them to have more opportunities to remove the chips. Of course this redundant system is expensive and the present tendency in the Automotive industry is to reduce the number of washers in the lines.

In any case the miracles are impossible and if you really check inside your cylinder head water jackets(or cylinder block water jackets) you have to pay attention to the whole manufacturing process including the more effective wash processes to remove the trapped chips and to have a really clean part.

 

A good system is to collect and classify all the chips shape produced in the machining line , operation by operation .  

And then looking to the chip type remaining inside the W.J. you can identify in which machining operation the chip is produced and penetrates in the W.J. Working with the machining process engineers it comes very often the possibility to reduce the size of the chip or to eliminate the quantity remaining in the parts

 

The automobile cleanliness tests procedures are also an interesting point to be examined in a further post. They are the reason why some time one washing machines that is a good machine for an automotive manufacturer but fails in another manufacturer.

Easy accessibility for maintenance

The washing machines for complex mechanical parts like the automobile cylinder block or cylinder heads are like machine tools with a lot of mechanics , hydraulics , pneumatics and electric components.

The reliability of the machine is directly linked with the good working of these components . These components are submitted to very bad conditions compared with a machine tool.Inside a washing machine there is a lot of bad conditions : dust air, humidity , temperature , vibrations, water spraying , chemicals( detergents) , coolants (coming with the parts to be washed) ,chips ,burrs ,.. The conditions are much worst than in a machine tool.

These conditions are very hard for the machine components and the engineering of a good washing machine has to consider as a first task to limit the components inside the washing machine.

This task is not always 100% possible and inside the machine there are also  mechanic components that have to be easy to maintain and repair. For this reason the second task of a good washing machine engineering is to take care of the accessibility to all the components around the machine.

Easy accessibility of the maintenance operator to all the components located outside the machine ( cylinders , mechanics, switches,valves, check valves , distributors…) and also to the inside the machine.

Depending of the machine size and the components inside the machine the accessibility can be made with large doors in order that the operator can access to the component keeping his foots outside the machine.

But in high production machines ,or big machines the operator has sometime to go inside the machine for the maintenance . For that, late 70’s the company Agullo launch a big innovation . A complete wall of the machine , all along the machine was a door with a vertical opening( big size guillotine door). The door received different names trough the times , vertical door , vertical guillotine door , full access side door, full size door … and was rapidly adapted by others manufacturers .

The first installations with these full size guillotine doors we supplied by Agullo to Peugeot and Renault in France . They were driven by a motoreducer and two chains on the top. The door opening was from the roof till the transfer .

The french competitor Stic Hafroy seen the machines in Peugeot and Renault quickly “adopted” this type of door in their machines.

The dimensions for the doors were growing in length (machines with 12mts doors length) and in heigth allowing to the operator to go and walk  inside the machine . Normally the machines were equipped with only one door in one side of the machine , but Agullo supplied also machines with two doors one in each side of the machine.

 

 

 

 

 

As one of the main customers was Ford Motor co. in UK and Germany the competitors in these countries also adopted the full size access door ( Harry Major  , Beys…).

 

 

 

Harry Major

 

In Italy for Fiat the machines had one full size guillotine door in one side of the machine and one corridor all along the machine in the other side allowing the operators to walk all along the machine both sides of the transfer.Seen the machines supplied to FIAT the local competitors Tecnofirma , and ICOM incorporated the door to their machines.

Agullo

 

 

 

 

 

Icom

 

Tecnofirma

 

 

The driving of these doors was progressing from the double chain and one reductor , to the rack and pinion , or gear and pinion and from the top driving to the floor driving , always by cost reduction reasons because the safety was never a concern .

In the 90’s  and 2000’s a lot of machines were supplied to Ford , Chrysler and GM  USA with these doors been accepted on all the customers safety standards.

 

Agullo-Dürr Ecoclean

 

 

                         Agullo/Dürr Ecoclean

 

 

 

In USA the full size guillotine door was also adapted by competitors like Valiant

 

Valiant

 

 

The challenge of these doors is not only the mechanics for the vertical movement for open/close the door but the water leaks and the noise contention. Any small gap on the adjustment to the machine wall could allow the water leaks outside the machine or to rise the machine noise level. The door construction, the materials used, and the design allows to avoid all those problems.

The high production machining lines in the automotive industry needs high efficiency and reduced cost. Few operators are operating the machining lines , and the first maintenance task are made by themselves . The machine needs to be easily controlled , and maintained . The design of the machine has to take in consideration the easy access to all the machine components , the easy and quick dis-assembly and repair . Full access , illumination , clean air, clean access .

Don’t forget : The washing machine needs maintenance because they work on worst conditions than the machine tools. It is a supplier task to reduce the maintenance time needed and also to allow the easy maintenance.

Robot cells : wash / deburr

In the STUTTGART Parts2clean exhibition , a lot of WASHER manufacturers were claiming their ability to supply robot applications for the wash and deburr process.

The application of robots in the wash/deburr is not new. Late in the 1980’s AGULLO was one of the first companies in the world to look for the application of these technologies. In this time the robots were mainly hydraulics or pneumatics and the main robot suppliers were the Americans UNIMATION ( Polar-articulated) and PRABB( cartesian) .

 To look closely to this applications I remember that I visited these two companies in USA , and both were proclives to decline any warranty of the robot working in the wet and dirt conditions of a washing machine.

Why? : The conditions inside a wash chamber are very inconvenient for the robot : water splash, possible direct contact with high pressure jet( 150 to 800 bars), hot ambient ( 50 to 70ºC), high humidity air , vapours , condensations ,  solids dirt , mechanical chock due to the chips removed from the part that can crash against the robot arms as bullets…

For the part gripper at the end of the robot wrist the same problems that for the robot : water , humidity, condensations, temperature, mechanical bullets… and additionally : problems for the electric switches and wiring , and pneumatic hoses ,controlling the open/close positions of the gripper. 

So de-couraging was the result of these visit to USA that in the AGULLO company it was decided to design a specific robot to respond to the difficult conditions of the wash/deburr operations. The Market was requesting machines able to wash different parts, in the same machine, and at low production and the robot could help for that. The classic washing machines had then wash box fixtures with pin point jets adapted to each part to be washed . If the parts to be washed were different , then it was necessary to change the wash boxes of the machine at each time that the new part arrived to the machine.

For certain machines like crankshaft washers , or cylinder head washers , it was possible to create one fixture that was carrying he wash boxes and then the operator could change the complete package for each new part. With the cylinder block washers the wash fixture becomes heavy and requested a lot of time and hand labour to be changed. A robot (despite his high price) could simplify the work with only a wash robot program to be stetted for each part.  

The result in 1983 was the design of a Cartesian robot , five axis ,with all their mechanics and servos on the opposite end of the arms( patented) .The payload was 350Kg and a prototype for validation was build in the Barcelona Agullo factory. Some of the customers robot experienced people visited the robot and gave some feedback. The most important  was coming from a Mercedes robot engineer suggesting to switch from the hydraulic servos( American Moog) of the prototype to the electric drive system as it was the future for the robots at least in Europe. The robotic electronic command was also another concern . Too much electronic companies offered robotic commands in the shows but they didn’t have experience in the field. By other side the customers didn’t like to train their people to each robotic command of the suppliers .

Another concern was also to consider if instead to grip the part to be washed to the robot arm , if it would be faster and agile to move the jet with the gantry robot and leave the part static. Then instead to need a 300Kg payload to move a cylinder block to wash and his gripper , we would need only a 50 or 70 Kg payload for the high pressure applications. Finally the decision was to re-convert the design to a Cartesian gantry robot with electric drive and servos with CNC controls ( Siemens or Allan Bradley the more popular then in the field ) and to move the jet. Totally a four axis gantry robot CNC controlled , working against the part to be washed presented in a fixture , or an in line transfer or a rotary table transfer. The fixture could have a supplementary CNC axis giving a total of five axis , enough for the wash/deburr process.

With this gantry robot located in the roof of the machine , with folded bellows to close the gap on the roof , all the mechanical an electrics of the gantry were outside the machine well protected against any water splash , or condensations. No mechanics neither electrics were on the wet area of the machine but all was outside the machine in the roof for easy access.The CNC command was controlling the gantry robot and the machine itself.

This AGULLO gantry robot was build for more than 17 years , around 100 units , and a derivative of it is still supplied by Dürr Ecoclean on some Rotary transfer washers for cylinder blocks and cylinder heads applications. There is one of these gantry robot 14 years old that is still working in his washer.

Why I have explained all these past experiences?  Because the alternative to the gantry robot using the articulated robots in the machines was difficult years ago. The first that I know were used the Smart-COMAU(Fiat) for the Borg Warner USA compressor applications but with the articulated robot outside the machine , vertical, on the floor, and with a complete vertical circular bellow wall to protect the robot. This bellow last normally no more than one year in normal conditions but with accidents or bad manual movements it has to be replaced very often. The english manufacturer CERA was also trying to use the same robot layout but with ABB robot.

In France Renault developed also one small vertical Cartesian robot that was used by the french company Brochot on the machines supplied to Renault to clean / deburr gear boxes but with many problems on the belows and mechanics, because the complete robot was inside the machine.

Fanuc was also marketing his small articulated robots for small wash applications ( first in japan and later in USA), but with frequent disassembling for maintenance.

Then ABB pushed also his robots . They were applied in the high pressure jet cutting located in the roof of the water-jet cabinets , and this application inspired to certain washer manufacturers to use the articulated robots inside the washing machines. 

 

Manufacturers like STIC_Hafroy in France and ICOM in Italy , Eurowide in England used the ABB in the roof with a big textile wrap ( moving the water jet).

Today the articulated robot suppliers have improved their robots and now they start to propose a better water protection to the end wrist and to the robot body . (As is the case of ABB and in a second place Fanuc,may be we could also add Staubli if his last robot runs well). In consequence there are more and more manufacturers that they propose “robotic washers” using standard robots of the market.

A lot of robot  suppliers assure IP67 protection for the robot ,but maybe we have to remember that IP67 protection in the robot is not enough for a wash deburr application . You would have to go to the “electrics standards” and see what means “IP67″ . The first digit”6″ means solids protection :”power dirt protection” .The second digit (“7″) is a water protection but “7″ means protection to the water inmersion without pressure for 30 minutes¡¡ Inside a wash/deburr cell , there is high pressure water ¡¡

Some robot suppliers claim higher protection :”IP68″ , but again please note that the digit ”8″ means “harder conditions (to be defined by the supplier) of immersion than the IP67″ but still immersion , not protection to the high pressure jets.

What means all that ?, that the washer manufacturer who is proposing to a client a “robot cell” with an articulated robot of the market needs to add some additional engineering to his machine for additional protection of the robot . If not, the client is taking a big risk ordering a machine to this washer  manufacturer. 

But there is still a confusion using the term “robotic washer”. What is better to move the jet with the robot or the part against the wash/deburr jet?. We will see in a next post…