Gantry wash robots vs. articulated wash Robots

The utilisation of robots in the washing machines began for the need to wash different parts in the same machine or the need to high pressure deburr of some areas of the parts .

The german Dürr Ecoclean starts to use the robots in their in-line transfer DGI machines as a complementary high pressure wash of  cylinder blocks or cylinder heads. The parts were transferred in a lift and carry transfer trough the machine an in one station it was the robot with the high pressure jet in the wrist that  works on the part. The robot was located vertical with base at the floor outside the machine with a complete glove on the arm to protect the robot arm inside the machine.

The same philosophy was applied by Stic-Hafroy (now Dürr Ecoclean) ,  ICOM , Valiant , ITF and others. But it happen also the application of deburring small parts like ABS distributors or injectors components where the robot ( or robots) were picking the parts from a pallet and presenting the parts in front of HP jets or lances . In this case the wrist of the robot had grippers for the part and no jets as before.

The”flexibility” of the machine in this case is coming from the possibility to have several wash/deburr programs inside the same machine , but the gripper of the robot need to have at least common points in the component to be washed in order to pick the parts.

Here is appearing the two different concepts on the robotic wash/deburr applications : a robotic wash/deburr operation with a jet moved by the robot against a part transferred by a mechanical system or a robot with a gripper picking the part and moving the part against HP wash/deburr fixed location jets.

In the first case( robot moving the jet) the robot is less exposed to the direct splash of water and there is no mechanical-pneumatic-electric components on the wrist.

 

In the second case (the robot moving the part) the robot wrist is exposed to receive direct high pressure splash , and it has mechanical-pneumatic-electric components on the part gripper risking to be wet .

Some people with experience in robot automation have plunge in the wash/deburr applications with robots gripping the parts without evaluating the additional risk on the wrist. The robot suppliers are working hard to protect the articulated robot but the maximum protection proposed is a IP65 for the arm , with stainless steel covers , and IP68 for the wrist( see my before “post” concerning the IP validity’s). Some of them they are also adding  air over pressure for the wrist. In any case in these applications there is much more risk than in the case of the robot moving the jet.

 In the before post I mentioned the advantages of the Agullo gantry moving the jet at the end of the vertical arm with all the mechanical outside the machine.

 

 

 

The same disposition is adapted by the japanese SUGINO . Sugino is living in the country with more robot suppliers of the world . Why Sugino is not using the articulated robot in their machines? : Because they are more confident with the gantry on the top of the machine than with a robot.

 

 

 

Other manufacturers like the german Arau has presented in the Parts2clean Stuttgart exhibition his robot cell using also a gantry in the roof of the machine. (years before it was using articulated robots inside the machine).Another example is the german Piller that is using the gantry on top of the machine for the HP deburr jet in his cells.

Another advantage of the gantry robot utilisation is that the machine has only one electric control: a CNC known by the users and easy to run. In the case of the articulated robots inside machines , the machine needs a PLC and the robot has his own electronic control( two controls units in one machine).

But the articulated robot has also good points :It can load/unload the part in the machine by himself  when the gantry robot moving the jet , needs of  another transfer device for the parts, it can be produced in advance and customised in the last moment (gripper and programme) ..

So , what a dilemma ¡¡… Yes , and there is another interesting point : the total investment for the machine.

The Robot cells with articulated robots carrying the part are as single  cell an “economic” machine compared with a transfer-robotic  in line machine , or a rotary transfer-robotic machine. But the throughput is not the same.

In a robotic cell loading and unloading the part with the articulated robot you have dead time( load/unload) that penalize the complete cycle of the machine . More big is the part to be washed ( heavier) more time you will spend on the load/unload( lower speed on the movements due to the inertia). The wash time and the blow-off /dry times can not be fully reduced and then there is a need to use several robotic cells according with the requested throughput production .That’s means that you will need two,four.. or five robotic cells versus one equivalent transfer in line or rotary transfer robotic machines.

As a general rule we can say that in the majority of the automotive cylinder blocks and cylinder heads applications the investment is higher with the robotic cells . But is also an strategic choice: you can have one robotic cell as spare , in case of a shutdown in another, or you can increase the production step by step buying the cells in several years … Interesting comparison.

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…

Part2clean Stutgart (4) Rotary transfer washers

Out of the already commented rotary transfer machines for small components , in the Parts2clean show I noted other manufacturers that they are active to wash or deburr bigger parts ( main powertrain components as cylinder block, cylinder head, crankshafts, gear box…).

Almost all the manufactures of these machines were German , and only few “foreign”. One of this foreign manufacturers was the Italian Tecnofirma. This company is an “old” company in the business. At the beginning mainly present in Italy . Years ago it started to wash cylinder block and cylinder heads Automobile components but the presence of AGULLO and ICOM in Italy stopped their development in the 1990’s . They were limited to crankshafts transfers or gear box components so long as AGULLO and ICOM had orders for the cylinder block and cylinder heads in line transfer washers for FIAT.

Tecnofirma developed rotary transfer washers for other components related to the motorcycles , tractors or gearbox components in Italy and also for the customer subsidiaries in Latinamerica or East Europe.. Now is improving his sales action in Germany and France , and they presented an interesting rotary transfer wash/deburr machine ( four stations) with an small ABB robot carrying a jet for the flex wash or blow-off.

 

 

 

 

The robot is applied directly inside of the wash chamber and has a jet on his wrist.

The High pressure pack and filter is installed in a separate module with the classic Hamelmann piston pump. The filtration is trough a safety cartridge filters and automatic paper filter

The machine has a robust look and the price announced seems interesting. Tecnofirma has a good experience in mechanical components customers. I hope that they can have a development in the next years if they achieve their export development.

Another of the “foreign” exhibitors was the Japanese SUGINO .This company has also a long history on the wash-deburr business. Their main market is the Japan companies and their transplants to other countries.

SUGINO has the best experience in high pressure applications in the wash and the deburr. Don’t forget that the Japanese automobile companies were the first ,worldwide ,to improve their cleanliness levels using high pressure water in their washers and after using also the high pressure for the deburring.This Market was advanced against the European or American markets.

SUGINOis the sole wash producer in the world, that I know ,that is also producing their high pressure pumps. In fact the division of high pressure pumps and his applications in all the industries is one of the hard points of Sugino. They have several patents and the advantage to produce themselves also the high pressure accessories ( 2ways valves, safety valves, HP jets, lances, distributors…).The use of the high pressure goes till to the jet cutting at 4.000 bars

Surprisingly despite their high experience and acknowledgement in the high pressure they have been not active in Europe. Their competitor KITO at least supplied Toyota in UK but Sugino has been out of this market. In USA they sold some machines 15 years ago in the gear box Ford factories but they din’t push too much the market and remain anecdotal.

Is really a pity because for me Sugino has experience , acknowledgement and inventive. Some tricky devices and original process invented by them ,and not yet discovered by the German suppliers( neither Americans), are fantastic and very efficient.

In the Parts2clean exhibition they presented the “Jet Clean Center”. Is a cell with CNC axis that allows to high pressure wash and high pressure deburr small components . These components can be manually load or robot load.

The must interesting thing of this machine is the Turret tool jet head. The turret has 6 possible different high pressure jets or lances that can be feeded individually trough a HP distributor. This machine is valid for small productions in a cell configuration and has been the first machine on this business to adapt the form of a High pressure cell , idea reproduced now for a lot of manufacturers.

 

SUGINO has also a family of rotary transfer machines for cylinder blocks and cylinder heads . The machine with two , three or four stations is integrated on in line or in cells productions . Recently they have supplied these machines for the new Mazda-Ford factory in China. They have a combination of the machine with a Cartesian 4 axis wash gantry robot located in the roof totally outside the machine as Durr Ecoclean Barcelona had.

The originality of their machine is that the load/unload of the parts can be made automatically without any further device .A vertical movement of the complete rotary table allows the part to be load/unload on a conveyor at the same time that the same vertical movement of the table allows to better wash and blow-off the parts in the other stations.

The application of the gantry robots instead of anthropomorphous robot in the high pressure wash-deburr applications is an interesting debate that I will write about in one further post after also a further robot cells post.

The weak point of these machines is that the indexing driving device with the vertical movement of the table is inside the machine , not easily accessible for maintenance. To do the same process the design of the Dürr Ecoclean Barcelona transfer rotary machine was much better solved with full accessibility to all the mechanics either rotary , lifting or gantry ( but more expensive of course).

In general the SUGINO wash-deburr processes , and high pressure devices are original,tricky and effective. The mechanical concept of the machine and their sizes are really designed for the Japanese Market . The design should be hardly modified to support the European rules and standards and by this reason is very difficult that some European client accept their machines standards. Is not their fault is a question of market demands. Something similar happened on the first machines supplied to Ford America.

But for markets like the Japanese or China, Korea..where the demand for big access for maintainability , and safety rules are not so stringent than in Europe , these machines are valid. But as the price is also important and these solutions are chipper, the client has to balance his decisions.

SUGINO has now a subsidiary in Chekia for his division of machine tools. It would be maybe a good opportunity for them to redesign their machines for the European Market demands.

OK ,that’s all for today. See you soon in my next post.

Parts2clean Stuttgart (3) Rotary transfer washers

One of my former customers , ask me why I have not talk about his Dürr Ecoclean rotary transfer washing machines in my last post.

Sorry¡¡¡ ,  effectively I supplied when I was in Dür Ecoclean an installation with three excellent rotary transfer washers to clean common rail injection pumps components at 2.000/300 bars that are today working 24h a day without problems.

The installation had a previous stage of high pressure deburr with robot at 2.000 bars followed of a rotary transfer machine with medium pressure spray wash,high pressure wash(300bar) with injection in contact and push pull system, spray , blow-off , vacuum dry . These machines are the top range in the field with central filtration and high pressures power units.The machines were designed and engineered by the Barcelona Dürr Ecoclean office team that was closed in 2007 but I’m not sure that these type of machines are still part of the Dürr Ecoclean catalogue. For this reason a I didn’t mention it in my last post that was dedicated mainly to the Parts2clean presentations.

Another innovative advantage of these machines was the flexibility as easy reconversion for new different parts. The pallet support on the rotary transfer table was of a quick change design. The clamping and High Pressure injection devices were of quick reconversion. The high pressure robot deburr( 2.000 bar operation) had automatic gripper change device with automatic grippers storage .

As maintenance features they had: total index driving system accessibility, total open doors for inside accessibility , quick change of internal components. The Centralised tank , filtration ,medium pressure pumps ,high pressure pumps ,very high pressure pumps , water treatment, and safety filters were installed in a remote area allowing to deserve three or more rotary transfer machines. This layout allowed to have a minimum surface layout on the working areas occupied by the machines itself , keeping the bigger floor surface of the tanks and pumps in the remote area . By other side this layout was an advantage for the maintenance people having all the pumps, valves,and filters in the same area for easy control and follow up..   

Neverless there is another type of Rotary transfer machines , the machines for powertrain components like cylinder blocks and cylinder heads by one side , and another simpler machines for gearboxes and crankshaft .

In my next post we will talk of the cylinder block and cylinder head rotary transfer machines.