A technical analysis of a special V450CM solution with 130 mm stroke, modified piston position and mechanical reference on the third plate
This article is the second part of the previous!
In complex injection molds, defining the cylinder stroke is not simply a matter of selecting a standard value from a catalogue.
The actual challenge can be much more precise: where must the moving plate stop, what component must define that position, and where should the resulting mechanical load be transferred?
This becomes particularly important when hydraulic cylinders are installed on a third plate of a 2+1 cavity injection mold and the customer requires the plate itself to determine the final mechanical position.
A previous article examined the broader integration of hydraulic cylinders on a three-plate mold, including stroke, rod geometry, mechanical stops, alignment and sensor selection. This article goes one step further and examines the technical development of the same application, focusing specifically on the definition of the lower end position and the modification required to obtain a 130 mm stroke.
The application ultimately led to a special configuration of a V450CM hydraulic cylinder, with a modified internal geometry and a 130 mm stroke. The Vega Technical Team also evaluated the mechanical sensor configuration required for the application.
1. Why defining cylinder stroke is more complicated than it appears
When a hydraulic cylinder is specified with a certain stroke, it is tempting to assume that this value automatically corresponds to the movement of the mold plate.
In reality, several reference points have to be considered:
- the cylinder body;
- the piston;
- the rod;
- the rod-end connection;
- the moving plate;
- the fixed plate;
- the mechanical end stop.
The important question is therefore not only:
How much does the cylinder move?
but:
Which component defines the final position of the mold mechanism?
This distinction became critical in the application examined by the Vega Technical Team.
The customer required approximately 130 mm of effective movement, while the initial geometry resulted in a configuration that would effectively provide 125 mm. The customer therefore asked whether the rod could be shortened by 5 mm.
2. The original requirement: 130 mm instead of 125 mm
The requested modification was driven by the geometry of the third plate.
The customer wanted the third plate to reach its final position while maintaining a 130 mm cylinder movement.
The initial proposal was therefore to shorten the rod by 5 mm.
At first glance, this appears to be a straightforward dimensional modification.
However, the subsequent technical analysis showed that the problem was not simply the length of the rod.
The actual issue concerned the reference used to define the end position of the complete mechanism.
That distinction changed the solution.
3. Why simply shortening the rod was not the correct solution
The first technical response was that the rod could not simply be shortened by 5 mm.
One possibility initially considered was to recess the rod into the third plate.
However, the customer’s subsequent clarification showed why this did not completely solve the underlying problem.
The relevant reference was not simply the physical end of the rod.
The customer needed the third plate itself to become the absolute mechanical reference for the lower end position.
The distinction is fundamental.
If the reference remains tied to the cylinder’s internal geometry or to the rod position, changing the external rod length does not necessarily establish the required absolute position of the plate.
4. Relative position versus absolute mechanical position
Consider two different references.
Relative reference
The position is defined in relation to the cylinder, piston or rod.
Absolute mechanical reference
The position is defined by the physical contact between the moving plate and another fixed component of the mold.
In this application, the desired solution was based on the second principle.
The customer wanted the third plate to reach a defined position against the fixed part of the mold while the cylinder continued to apply the required force.
This meant that the internal geometry of the cylinder had to be considered.
5. The real problem was the cylinder bottom
The subsequent technical clarification changed the direction of the solution.
Instead of simply modifying the rod, the important dimension became the position of the cylinder bottom relative to the piston.
The customer explained that the cylinder bottom needed to be moved by approximately 1–2 mm so that the lower limit would be determined by the third plate rather than by the cylinder itself.
This is the key technical point of the entire application.
The objective was not simply to create 5 mm more physical space.
The objective was to establish the correct load path and mechanical reference.
6. The intended load path
The customer’s explanation made the desired load path particularly clear.
At the lower mechanical position, the force should not be transferred from the piston directly into the bottom of the cylinder.
Instead, the piston should continue to apply force through the rod and into the third plate.
The third plate would then be mechanically supported against the fixed plate of the mold.
Conceptually, the desired arrangement is:
Hydraulic pressure
↓
Piston
↓
Rod
↓
Third plate
↓
Fixed plate / mechanical reference
Rather than:
Hydraulic pressure
↓
Piston
↓
Cylinder bottom
This distinction is essential.
7. Why the piston must not bottom out against the cylinder
If the piston reaches the cylinder bottom before the mold plate reaches its intended mechanical reference, the cylinder itself becomes the limiting component.
That creates a different mechanical condition.
The customer wanted the mold structure, rather than the internal end of the hydraulic cylinder, to determine the final position.
This is why moving the cylinder bottom away from the piston by a small amount became important.
The objective was to guarantee that the cylinder would still have the necessary internal clearance when the third plate reached its mechanical position.
8. Creating a 1–2 mm clearance
The proposed approach was therefore to create approximately 1–2 mm of additional clearance at the cylinder bottom.
This meant that when the third plate reached its mechanical stop, the piston would not simultaneously bottom out against the cylinder body.
Instead, there would remain a controlled internal clearance.
The subsequent Vega proposal specified an adjustment of 1.5 mm on the piston side opposite the rod outlet.
This 1.5 mm dimension represents the refined technical solution that emerged from the discussion.
9. Why 1.5 mm is significant
The modification may appear very small.
However, its function is not to increase the cylinder’s stroke by 1.5 mm in a conventional sense.
Its purpose is to change the relationship between the piston and the cylinder bottom at the end of the mechanical movement.
The 1.5 mm modification establishes the necessary separation between:
- the piston;
- the cylinder bottom;
- the mechanical reference provided by the mold.
This is a good example of how a small dimensional change inside a hydraulic cylinder can have a major effect on the mechanical behavior of the complete mold mechanism.
10. The third plate becomes the true mechanical reference
Once the cylinder geometry is modified appropriately, the third plate can reach its intended mechanical position without the piston simultaneously contacting the cylinder bottom.
The resulting concept is:
Third plate moves
↓
Third plate reaches fixed mechanical reference
↓
Cylinder still has internal clearance
↓
Hydraulic force remains available
This is fundamentally different from designing the cylinder so that its internal end position determines the mold position.
11. Why this is important for mold designers
When a hydraulic cylinder is used to move a mold plate, the designer should decide explicitly:
Is the final position determined by the cylinder, or by the mold structure?
Neither solution is automatically correct for every application.
But if the mold structure must define the final position, the cylinder must be designed so that its internal geometry does not interfere with that mechanical reference.
That was the essential issue in this application.
12. The importance of the force path
The force path is just as important as the position.
At the lower end position, the hydraulic pressure continues to act on the piston.
The piston transfers this force through the rod to the third plate.
The third plate is then mechanically supported by the fixed part of the mold.
The cylinder therefore acts as the actuator maintaining the force, while the mold structure determines the final mechanical position.
This is a much more precise way of describing the function of the cylinder in this application.
13. Why the rod needed to be slightly longer
Once the cylinder bottom was moved relative to the piston, another practical consequence had to be considered.
The customer proposed making the rod slightly longer so that the rod would not retract into the cylinder when the cylinder was removed from the mold.
This is an important practical detail.
The cylinder has to function correctly not only while installed in the mold but also during:
- assembly;
- disassembly;
- maintenance;
- handling.
The rod length therefore had to be coordinated with the modified internal geometry.
14. The rod and the third-plate locking geometry
The modification also affected the geometry of the third plate.
Because the rod would be slightly longer, the counterbore / locking recess in the third plate also had to be increased accordingly.
This demonstrates an important engineering principle:
A modification to one component can propagate through the complete mechanical assembly.
Changing the piston position affected:
- cylinder internal geometry;
- rod length;
- third-plate geometry;
- rod retention;
- assembly conditions.
15. The solution was therefore not simply a “longer stroke”
It would be misleading to describe the solution simply as:
“Vega increased the cylinder stroke.”
The technical modification was more specific.
The customer needed:
- a 130 mm movement;
- a mechanical reference on the third plate;
- clearance between piston and cylinder bottom at the final position;
- continued hydraulic force on the piston;
- appropriate rod geometry.
The final solution addressed all of these requirements simultaneously.
16. The V450CM platform
The V450CM is Vega’s compact Heavy Duty short-stroke hydraulic-cylinder series.
The official product documentation describes the standard V450CM range as compact cylinders with a steel body and single rod, available in standard bore and stroke configurations.
The series is intended for applications including movement of:
- carts;
- pins;
- plugs;
- mold ejection plates.
This makes the V450CM a relevant platform for applications in which a compact cylinder must generate substantial hydraulic force within a limited mold space.
17. The 130 mm stroke required a special configuration
An important detail from the technical correspondence is that 130 mm was not treated as a standard V450CM configuration for this application.
The Vega Technical Team confirmed that the cylinder could be produced with the required 130 mm stroke as a special version, together with the internal modification discussed above.
This distinction should be maintained clearly.
The standard product range should not be confused with a customer-specific special configuration.
Vega also officially states that it produces custom hydraulic cylinders when standard configurations do not meet the customer’s requirements.
18. Why special cylinders can be necessary in mold engineering
Injection molds frequently contain very specific dimensional constraints.
A standard cylinder may provide:
- the correct force;
- the correct general geometry;
- the correct sensor technology;
but still require a special dimensional configuration because of the mold architecture.
In this case, the required 130 mm movement and the particular mechanical reference demanded a special V450CM configuration.
This is a good example of where customization is not about creating a completely different cylinder.
It can instead involve precise modifications to an established cylinder platform.
19. Sensor configuration
The final configuration also included a Vega mechanical sensor.
This is consistent with the V450CM architecture.
Because the V450CM has an all-steel body, Vega’s official documentation explains that magnetic sensors are not used for this cylinder and that mechanical switches are the appropriate solution.
Vega offers several mechanical-switch configurations for the V450CM, including versions designed for different temperatures and installation arrangements.
20. Why sensor selection must be integrated into the design
The sensor does not define the mechanical stop.
Instead, it provides the machine with position information.
The distinction is important:
Mechanical structure
→ determines where the plate physically stops.
Sensor
→ confirms the position to the control system.
This allows the mold control system to verify that the expected position has been reached.
21. Mechanical reference and electrical feedback
A robust mold design can therefore combine two independent functions:
Mechanical positioning
The third plate reaches the fixed mechanical reference.
Position monitoring
The mechanical switch confirms the cylinder position.
The two systems complement one another.
The sensor should not be considered a replacement for the mechanical stop, nor should the mechanical stop be considered a substitute for position feedback when the machine requires it.
22. Why the cylinder bottom modification is more important than the rod modification
The initial problem appeared to be a rod-length problem.
The final analysis showed that it was primarily a reference-position problem.
This is perhaps the most valuable engineering lesson from the application.
The question evolved from:
“Can we shorten the rod by 5 mm?”
to:
“How can we ensure that the third plate, rather than the cylinder bottom, defines the final position while maintaining the required hydraulic force?”
The second question leads to a fundamentally better engineering solution.
23. Designing from the required load path
A useful approach for similar applications is to work backwards from the desired mechanical condition.
First determine:
Where must the plate stop?
Then:
What component must physically support it?
Then:
Where must the hydraulic force be transmitted?
Finally:
What cylinder geometry is required to make those conditions coexist?
In this application, the answer was:
- the third plate defines the position;
- the fixed mold structure provides the mechanical reference;
- the piston continues to apply force through the rod;
- the cylinder bottom remains clear;
- the V450CM is modified accordingly.
24. The importance of avoiding unintended bottoming
Hydraulic cylinders can reach the end of their physical stroke internally.
But if the mold mechanism has its own mechanical stop, these two positions must be coordinated.
If the mold reaches its mechanical stop before the piston reaches the cylinder bottom, the cylinder can continue to provide the required force without the piston itself becoming the limiting mechanical element.
If the piston reaches the bottom first, the cylinder becomes the limiting component.
The design objective in this application was clearly the former.
25. Small dimensional changes require complete system verification
The final 1.5 mm adjustment illustrates how precision mold engineering works.
A modification of only a few millimetres affected:
- piston position;
- cylinder bottom clearance;
- rod length;
- third-plate counterbore;
- final stroke;
- assembly behavior.
This is why modifications to hydraulic cylinders for molds should be evaluated as complete system changes, rather than isolated dimensional edits.
26. The connection to the previous three-plate mold article
This application is directly related to the earlier technical discussion about hydraulic cylinders on three-plate injection molds.
The previous article focused on the broader integration of:
- cylinder stroke;
- third-plate movement;
- rod geometry;
- mechanical stops;
- alignment;
- sensor selection.
The present article goes deeper into one specific engineering question:
How can the mechanical end position be transferred from the cylinder to the mold structure without losing the required hydraulic function?
Because the exact URL of the previously published article was not available in the source material or returned by the current web search, I would not invent a URL for it. Once the article’s published URL is known, this paragraph can be linked directly to it.
27. The V450CM and special-project philosophy
Vega’s official custom-cylinder documentation confirms that the company produces special V450CM configurations for customer-specific applications.
This is particularly relevant to complex injection-mold applications.
A special project does not necessarily mean redesigning the entire cylinder family.
It can mean adapting:
- stroke;
- mounting;
- rod geometry;
- internal dimensions;
- sensor configuration;
- connection;
- other customer-specific requirements.
The application discussed here is an example of that type of engineering approach.
28. What the Technical Team actually solved
The Technical Team did not simply solve a dimensional interference.
It solved four interconnected problems:
1. Stroke
The application required 130 mm.
2. Mechanical reference
The third plate had to determine the final position.
3. Force transmission
The piston had to continue transmitting force to the plate without bottoming against the cylinder.
4. Assembly
The rod and third-plate geometry had to remain practical during installation and removal.
The final special V450CM configuration addressed these requirements together.
29. Practical checklist for similar applications
When designing a hydraulic cylinder for a three-plate mold, ask:
Stroke
- What movement is actually required?
- Is the required stroke standard?
- Is additional stroke available as a special configuration?
Mechanical reference
- What component defines the final position?
- Is the reference the cylinder or the mold structure?
Piston
- Can the piston reach the cylinder bottom?
- Is sufficient internal clearance maintained at the mechanical stop?
Rod
- Is the rod long enough?
- Does it remain safely positioned during cylinder removal?
- Does the rod-end geometry fit the mold?
Third plate
- Is there sufficient space for the rod?
- Is the counterbore deep enough?
- Does the plate provide the intended mechanical support?
Sensor
- Which sensor technology is compatible with the cylinder?
- Where will the sensor be positioned?
- Can the control system reliably detect the required position?
Final assembly
- Has the complete 3D assembly been checked?
- Are all clearances verified?
- Is the load path correct?
30. The broader engineering lesson
The most important lesson from this application is that stroke is not merely a number.
A 130 mm cylinder stroke can have very different mechanical implications depending on:
- where the cylinder is mounted;
- where the piston stops;
- where the rod connects;
- where the plate stops;
- which component absorbs the mechanical reaction;
- how the hydraulic force is transmitted.
In this application, the difference between 125 and 130 mm could not be solved correctly by simply removing 5 mm from the rod.
The complete mechanical reference had to be reconsidered.
31. From a dimensional problem to a load-path solution
This is the key evolution of the design.
Initial interpretation
The rod is 5 mm too long.
Deeper analysis
The mechanical reference is not located where it needs to be.
Final engineering approach
Modify the cylinder geometry so that the third plate defines the final position while the piston continues to transmit hydraulic force.
This progression is a valuable example of engineering problem-solving in injection-mold applications.
32. Conclusion
This application demonstrates how a seemingly small dimensional requirement can require a detailed analysis of the complete hydraulic and mechanical system.
The customer needed 130 mm of movement and wanted the third plate to establish the final mechanical position. The initial idea was to shorten the rod by 5 mm, but the subsequent technical discussion showed that this would not address the fundamental reference problem.
The important requirement was to ensure that, at the lower mechanical position, the third plate would provide the physical reference while the piston would continue to transmit force through the rod. The cylinder bottom therefore had to be moved away from the piston by approximately 1–2 mm.
The final technical proposal specified a 1.5 mm modification on the piston side opposite the rod outlet, together with the required 130 mm stroke as a special V450CM configuration.
The rod geometry and the counterbore in the third plate also had to be coordinated with the modification, while the final configuration included a Vega mechanical sensor.
The V450CM is officially described by Vega as a compact Heavy Duty hydraulic cylinder designed for short-stroke applications such as moving carts, pins, plugs and mold ejection plates. Its all-steel construction also explains the use of mechanical switches rather than magnetic sensors.
The central engineering lesson is therefore:
When a hydraulic cylinder is used to move a mold plate, the correct stroke is not defined only by the distance the rod travels. It must be defined together with the mechanical reference, piston position, load path and geometry of the mold.
In demanding applications, a few millimetres can determine whether the cylinder itself becomes the mechanical stop or whether the mold structure performs that function as intended.
Useful and verified URLs
I have kept these to official Vega websites and used the English versions where the article is in English.
1. V450CM – Short-Stroke Compact Hydraulic Cylinders
The main product page for the V450CM series, including its application range, construction, stroke options and sensor configurations.
2. V450CM – Product Configuration
V450CM Block Cylinder – EGM configuration
Useful for readers who want to examine a specific V450CM configuration.
3. Mechanical Switches for V450CM
Mechanical Switches – Vega Cylinders
Explains why mechanical switches are used on the all-steel V450CM and describes the available switch options.
4. MS5 Mechanical Switch
MS5 Mechanical Switch – Vega Cylinders
Technical page for the MS5 mechanical switch used with V450CM configurations.
5. Hydraulic Cylinders for Injection Molds
Vega Cylinders – Hydraulic Cylinders for Injection Molds
Official overview of Vega’s hydraulic-cylinder range for plastic injection molding and die casting.
6. Hydraulic Cylinders for Ejection-Plate Movement
Hydraulic Cylinders for Ejection Plate Movement
Particularly relevant to applications involving hydraulic movement of mold plates.
7. Custom Hydraulic Cylinders
Custom Hydraulic Cylinders – Vega Cylinders
Useful for explaining why a special V450CM configuration can be developed when a standard cylinder does not meet a particular mold requirement.
