I'm glad you asked this question, because it is one that I hear a lot in my shop. The machine I am referring to is a modern grinding machine, and the cycle time is the time that it takes for the machine to complete one revolution of its work spindle when the control valve inlet pressure is fully opened.
The cycle time, as I assume you are referring, is the time it takes to open the second set of slides (slides 2) when the machine is cycling. Cycle times are typically measured in seconds and can be divided into two parts: (1) from the time that slide 1 opens until slide 2 opens and (2) from the time that slide 1 closes until slide 2 closes.
To reduce cycle times for this type of grinding machine, consider increasing feed rates and speeds by using a higher-torque motor or larger slides with better bearings. The best way to determine whether this would benefit your application would be to measure your current cycle times so you can see if they fall within industry standard ranges for similar applications!
There are several areas that you can look at to reduce the cycle time:
Are you using a coolant flush? If so, what kind of flush are you using? Some may be more efficient than others.
You should only use a coolant flush that is recommended by the machine manufacturer. If you don't have access to that information, call the company who sold your machine and ask them specifically which type of flush they recommend.
Is your slide gibbing in good condition? By this I mean tight and not worn.
If the gibs are loose or worn, they will allow for play in the slides and therefore increased cycle time.
What is the speed ratio from your hydraulic pump to the motor driving your grinding spindle? In most modern grinding machines, the hydraulic pump and the drive motor for the grinding spindle are on the same shaft. This allows for high-speed machining. If this is your situation, then your pump-to-motor speed ratio should be checked and adjusted if necessary.
The relationship between a motor and a pump's rotational speeds is called its "speed ratio." The typical speed ratio for a hydraulic grinder is about 3:1 (3:1). That means that for every revolution of the motor shaft, there are three revolutions of the shaft driving your grinding spindle. Thus, if you're running at 10,000 rpm in an attempt to reduce cycle time or increase part production rate (because both rpm and feed rate have been increased), then each revolution of that same drive system must be 30% faster than what it was before—a total of 40%.
Have you lubricated any bearings lately? How about slideways, etc.? A lack of lubrication will increase friction. Increased friction increases load on motors, pumps, etc., which will take longer to complete a cycle.
Lubricants are used to reduce friction between moving parts (i.e., the sliding jaw) and keep them from wearing out prematurely. The reduction in wear helps to lower maintenance costs by extending the life of expensive components like bearings or other moving parts like slides or motors.
It is frustrating if you are trying to reduce cycle time on your grinding machine, but it can be done. If you follow these steps and troubleshoot where your bottlenecks are, then you should be able to reduce the cycle time significantly. I hope this helps!