 Hello students, so myself, Siddhaswar B. Tulsapure, Associate Professor, Department of Mechanical Engineering, Walsh and Institute of Technology, Sulapur. So in this session, we are dealing with the sequencing circuit, the learning outcome. At the end of this session, students will be able to draw sequencing circuit and explain its working. The contents are introduction, sequencing circuit during forward stroke only, sequencing circuit during both strokes that is forward and backward and lastly the references. Let us have first the introduction to this sequencing operation. Now there are different say operations or processes in the industries which require to be performed one after the another one that is unless and until certain operation it is completed, the second operation cannot be performed or another operation cannot be performed. A simple case we will take, so a process we will consider that is drilling a hole in a work piece or a job. So in case of this one, the sequence of operation we are writing, first operation it is going to be the clamping of work piece, then drilling of hole, then it is withdrawal of drill, then declamping of the work piece. Like these four different operations are there which are to be performed in a particular sequence. Now we will firstly deal with the sequencing circuit during forward stroke only. So here we are going to make use of the linear actuators that is cylinder and piston and we will have forward stroke and backward stroke. So during forward stroke only, we are going to have the sequencing. So the same operation but you can observe that now the third operation it has been combined with the fourth one that is withdrawal of the drill and declamping of the work piece. So these are combined and we are having only say forward stroke as separate and one after the another one and forward stroke these are completed, then the say backward stroke it is going to take place for both the actuators at the same time. Now say we are having two cylinders or two actuators corresponding to these two operations that is when it is clamping and the second one it is the drilling and now we are going to have one wall which is called as sequence wall which is to be connected at a proper place. If the connections are wrong, the desired output may not be achieved. Now see this one. So this is a sequence wall. Sequence wall is a wall which belongs to the pressure control group. So in case of this one, so we are having one inlet port and one outlet port on the left hand side inlet port is there and on the right hand side it is outlet port is there. So now in case of this we are going to have the connection as, so inlet port it is connected to the say cap end of the clamping cylinder and outlet port it is connected to the cap end of the drilling cylinder. So you can observe that we are having the line from the rod end side of the clamping cylinder and rod end side of the drilling cylinder say mating each other and they are going to the port B of the direction control wall and B to T say that is the T port and from there it will go to the reservoir. So now we are having say P connected to A in the present condition and one line it is taken to the cap end of the say clamping cylinder say like this. Now let us have the first operation. So in case of the say hydraulic circuits or pneumatic circuits also you have to trace the path of the fluid. So now P is connected to A, so it is going in this direction till here the path is common. From here the oil goes to the say sequence wall and also check wall but sequence wall it is normally closed wall and check wall is also closed here because ball like structure it is coming first and then it goes to the clamping cylinder. The clamping cylinder piston it is going to move towards the right hand side and clamping operation will be done which is the first operation. See now the oil which is returning from the rod end side of the clamping cylinder it will return to the port B and B to T it will go. So this is the first operation. So once the clamping operation is over we are going to have the say pressure will be built up and this wall it is going to open inlet of this port it will be connected to the outlet port and from here it will go to the cap end of the drilling cylinder and piston it is going to move forward and we are having the drilling operation. So the oil it is returning to the port B and B is connected to T. During the say return stroke we are having the shifting of this pool with the help of the solenoid operation and you can observe that now P is connected to B from here the oil supply to the rod end of the both the cylinders it is taking place at the same time. So the piston of the drilling cylinder and piston of the clamping cylinder both are moving at the same time and withdrawal of drill and declamping operation. So these are taking place simultaneously. So this is the third operation and see the oil which is returning oil from the cap end of the cylinder it will return directly to the port A and from A it goes to the T whereas the oil from the drilling cylinder so it comes through the say it is check wall and then it is going to the say port A and A is connected to the T. So that is what the use of this check wall is. Now think of in which situation the withdrawal of drill and declamping can be done simultaneously. See these two are the different operations withdrawal of drill and declamping in say during which situations we can go for the combination of these that is these processes will occur simultaneously. See now the answer is withdrawal of drill and declamping can be done simultaneously when jobs are to some extent heavier, chips are broken and there is no jamming of the chips in the job or the workpiece. In this case when the simultaneous operations these are carried out that is declamping and say withdrawal of drill. So job will not be lifted by the drill and drill head assembly etc. So in case of the cast iron you can see that the chips these are broken. So cast iron it is brittle material. So if the materials are brittle and then next to that one to some extent heaviness if it is there. So we are we can go for the combination to save the time. Otherwise say withdrawal of drill it is to be done first and then we should go for the say declamping operation. Now let us have these four operations now separately that is third and the fourth we are also going to separate say instead of having the combination and the first one and the second one these are going to be always different. So we are having now four different operations. Now when four different operations these are to be carried out separately and one after the another one so and we are having these two actuators. So we should have two sequence walls instead of the say one sequence wall. So now let us go for the first say operation that is the clamping. So in case of this see now we are having one sequence wall and we are having one more sequence wall. Now the connections you should observe. So in case of the connections we are having say the inlet port connected to the cap end here and the outlet port connected to the cap end here. So same is the case for the second say sequence wall. Now inlet port it is connected to the rod end here so it is outlet port it is connected to the rod end here. See the inlet ports and outlet ports these are having the same connections that is either cap end cap end or they are having rod end rod end. The thing is what is going to decide that sequence of operation is say inlet is connected to which cylinder and outlet is connected to the which cylinder. Now in case of the second sequence wall you can observe that we have drawn it in somewhat reverse fashion to reduce the say complexity in case of the lines which we are showing here which are the working lines or the pipelines. So here it is simply say going to the rod end of the drilling cylinder. So in case of the say second sequence wall so we are having the inlet connected to the rod end of the drilling cylinder and outlet connected to the rod end of the clamping cylinder. You can draw this wall also similar to this one but the only thing is say you are going to have the lines to some extent of larger length and you have to say take it to larger distance and then you have to return etc. So like that the things will be to have the simplicity the reversal of this one is done which is going to reduce the complexity in drawing the working lines. Now we can have the drilling of the say the drilling cylinder we are going to consider now and the forward stroke of that one. See now the supply to the clamping cylinder was there and forward stroke has been completed now and say this inlet and outlet ports these are interconnected now and we are having say the supply to the cap end of the drilling cylinder. Then the piston of this one it is going to move and the oil returning you can trace. So it is passing through the check wall of the second sequence wall and in case of the say the second cylinder that is drilling cylinder so the oil is returning directly. In case of the withdrawal of drill we are having say the spool shifting P is connected to B then supply to the say this drilling cylinder it goes to the rod end say piston of this one it is going to come the sequence wall it is normally closed. So firstly the withdrawal of the drill it is going to take place once the pressure is developed sequence wall it is going to open and then we are going to have the flow through this sequence wall and it will go to the rod end of the clamping cylinder and piston it is going to come to the original position. The oil from here it will return directly to the port A and A is connected to T whereas the oil from here it is returning through the check wall of the sequence wall number one and it is going to the A and A is connected to T. So like this we are having separate say operations say four operations if these are there and all four these are to be say done separately we require two sequence walls and say in case of the say third and the fourth operation these are combined we can have one sequence wall say declamping. So that say this wall when opens suggest the diagram it is shown and the piston it is going to come back and the flow it is going to the A and A is connected to the T. So the references used are so these two thank you.