A Practical Vega Technical Guide for Mold Designers
Mechanical end-of-stroke switches are widely used to detect the position of hydraulic cylinders in injection molds, die-casting molds and other industrial applications.
However, when a mechanical switch is used, it is not enough to know the cylinder stroke.
The designer must also understand where the mechanical contact pin is positioned, how far it can be compressed, and within which range the microswitch must be activated.
A Vega technical case from June 2015 provides a useful example. The customer requested information about the operating range of a mechanical sensor, and Vega Technical Department supplied a revised drawing specifically showing the working range of the mechanical sensor. The technical team also planned additional tests on samples supplied by the customer.
The attached drawing identifies the relevant dimensions for the mechanical sensor and specifies the area in which the compressed pin must activate the microswitch.
This case is useful because it shows an important principle:
When designing the mechanical interface between a mold and a hydraulic-cylinder switch, the position of the switch pin must be controlled just as carefully as the cylinder stroke itself.
1. What Is a Mechanical End-of-Stroke Switch?
A mechanical end-of-stroke switch detects the position of a hydraulic cylinder through the physical movement of a contact pin.
Instead of detecting a magnetic field or measuring an electrical signal directly from the piston, the mechanical switch is actuated when a mechanical element reaches the required position.
Vega currently offers mechanical switches specifically for hydraulic-cylinder applications. The Vega range includes mechanical switch solutions for different cylinder configurations, including the MS5, MS6 and MS7 families.
Mechanical switches are particularly useful in applications where:
- the cylinder body is made of steel;
- magnetic detection is unsuitable;
- the cylinder operates at elevated temperatures;
- a direct mechanical position signal is required;
- the switch must be integrated into a compact mold installation.
For example, Vega’s V450CM hydraulic cylinders can be configured with mechanical switches, with different switch arrangements available depending on the cylinder version.
2. Why Is the Mechanical Switch Operating Range Important?
A common mistake when designing a mold is to consider only the nominal cylinder stroke.
For example, a designer may specify:
Cylinder stroke = 50 mm
and assume that the switch will automatically detect the end position at exactly 50 mm.
This is not necessarily how a mechanical switch should be treated.
The switch has its own mechanical operating characteristics.
The important dimensions include:
- the position of the contact pin when it is not compressed;
- the amount by which the pin is compressed;
- the position at which the microswitch is activated;
- the available mechanical travel;
- the position of the mold component that contacts the pin.
The Case 153 drawing was specifically created to define this operating range of the mechanical sensor.
3. The Vega Case: Range of the Mechanical Sensor
The original technical correspondence is dated 5 June 2015.
The Technical Department sent the customer a revised drawing showing the working range of the mechanical sensor and stated that additional tests would be performed on samples supplied by the customer.
This is important because it demonstrates that the operating range was treated as a specific technical parameter rather than simply assuming that the microswitch would operate at an arbitrary position.
The drawing identifies the sensor pin and provides dimensional references for its open and compressed conditions.
4. The Open Position of the Contact Pin
The drawing specifies the position of the contact pin in its open condition as:
3.4 +0.1 / −0.1 mm
This means that the nominal dimension is 3.4 mm, with the specified tolerance.
Therefore, the allowable dimensional range is:
- minimum: 3.3 mm
- nominal: 3.4 mm
- maximum: 3.5 mm
This dimension is shown directly on the Case 153 drawing.
For the mold designer, this provides a reference point from which the switch’s mechanical operating range can be understood.
5. The Drawing Also Identifies the Activation Field
The most important annotation on the drawing states:
“field in which the compressed pin must activate the microswitch.”
The drawing identifies this operating field using the dimensions shown around the contact pin.
The drawing shows two additional dimensional references:
0.5 mm
and
0.8 mm
These dimensions define the relevant operating area of the mechanical contact and should be interpreted together with the drawing geometry rather than as independent cylinder-stroke dimensions.
This is an important distinction.
The 0.5 mm and 0.8 mm values belong to the mechanical switch activation geometry shown in the drawing.
They should not automatically be interpreted as:
- cylinder stroke;
- switch hysteresis;
- electrical switching delay;
- total contact travel.
The Case 153 drawing does not provide those broader interpretations.
6. The Correct Way to Read the Drawing
The drawing should be understood as a mechanical interface specification.
It tells the mold designer approximately where the external component acting on the switch must position the contact pin.
The design sequence is therefore:
Hydraulic cylinder
→ mechanical switch
→ contact pin
→ mold component
→ defined pin compression
→ microswitch activation
The goal is to ensure that the mold component physically reaches the contact pin in the correct position.
7. The Mold Component Must Not Simply “Push the Pin”
A common design mistake is to assume:
“As long as the mold component touches the switch pin, the switch will work.”
This is not sufficient.
The contact pin must be compressed within the specified operating field.
Too little compression may fail to activate the microswitch.
Too much compression can move the pin outside its intended mechanical operating condition and may create unnecessary mechanical stress.
Therefore, the mold designer should establish a controlled mechanical position rather than relying on an approximate contact.
8. Why Tolerances Matter
The drawing specifies the open-pin position with a tolerance:
3.4 +0.1 / −0.1 mm.
This is important because mold components also have manufacturing tolerances.
If the switch itself has a permitted dimensional variation and the mold component has its own tolerance, the final position of the contact pin can vary.
For example, a designer should consider:
- cylinder mounting tolerance;
- switch mounting tolerance;
- mold machining tolerance;
- position of the moving component;
- thermal expansion where relevant;
- assembly tolerance.
The objective is not simply to obtain the correct nominal dimension.
The objective is to ensure that the actual assembled position remains inside the required operating field.
9. Nominal Position vs. Operating Range
This distinction is essential.
A drawing may provide a nominal dimension such as:
3.4 mm
but the microswitch does not necessarily operate at only that one theoretical position.
Instead, the drawing defines a range within which the compressed pin must activate the microswitch.
Therefore:
Nominal dimension
A reference position used for the mechanical design.
Tolerance
The permitted variation around that nominal position.
Operating field
The range in which the compressed pin must activate the microswitch.
These three concepts should not be confused.
10. Why This Matters in Injection Mold Design
Hydraulic cylinders used in molds often control:
- slides;
- cores;
- pins;
- plugs;
- shut-off components;
- ejection systems;
- other moving mold elements.
The cylinder may therefore be responsible for moving a component to a very precise position.
The machine controller may then use the mechanical switch signal to determine whether the cylinder has reached the required position.
Vega’s current hydraulic-cylinder range includes cylinders equipped with mechanical, inductive and magnetic position sensors depending on the model.
For example, the V450CM range uses mechanical or inductive switches to control cylinder stroke and transfer the signal to the injection-molding machine.
Consequently, correct mechanical positioning of the switch is an important part of the mold design.
11. The Switch Is Not the Same as the Cylinder Stroke
This deserves particular attention.
Suppose a cylinder has:
100 mm stroke
That does not mean that the switch contact pin should necessarily be compressed by 100 mm.
The cylinder stroke defines the movement of the hydraulic piston and rod.
The mechanical switch has its own contact mechanism and operating range.
The relationship between the two must be established through the mechanical installation.
A simplified representation is:
Cylinder reaches end position
↓
Mold component reaches switch pin
↓
Pin is compressed
↓
Pin enters specified activation field
↓
Microswitch changes state
The mechanical switch therefore acts as a position-detection interface between the hydraulic cylinder and the machine control system.
12. What Happens if the Pin Is Not Compressed Enough?
If the mold component stops before the required activation position, the microswitch may not be activated.
The possible result is that the machine receives no confirmation that the cylinder has reached the intended position.
Depending on the machine control logic, this could result in:
- a missing position signal;
- an incorrect sequence;
- a machine alarm;
- an interrupted cycle;
- incorrect mold movement.
The Case 153 drawing specifically defines the field in which the compressed pin must activate the microswitch.
Therefore, the designer should not rely on a visual approximation of the switch position.
13. What Happens if the Pin Is Compressed Too Much?
The opposite situation also needs to be avoided.
The mechanical switch is designed to operate within a defined mechanical range.
If the mold component continues pushing the pin after the intended operating position, the designer may create unnecessary mechanical loading.
Therefore, a good design should provide:
- controlled contact;
- correct activation;
- appropriate mechanical stop;
- no unnecessary over-compression.
The Case 153 drawing should be used as the dimensional reference for the specific sensor configuration.
It should not be assumed that an unlimited amount of additional compression is acceptable.
14. The Importance of the Mechanical Stop
A mechanical stop can be particularly useful in applications where the mold component repeatedly actuates the switch.
The purpose of the stop is to ensure that the moving component reaches a repeatable position.
The sequence becomes:
- cylinder moves;
- mold component approaches the switch;
- contact pin is compressed;
- microswitch is activated;
- mechanical stop establishes the final position.
This can improve repeatability and prevent unnecessary movement beyond the intended switching position.
The exact stop dimension should, however, be established according to the relevant cylinder and switch drawing.
15. The Four Sensor References Shown on the Drawing
The Case 153 drawing identifies:
MSA – MSB – MSC – MSD
and states:
“The expressed values are identical for sensor: MSA – MSB – MSC – MSD.”
This means that the dimensional values shown in the drawing apply consistently to these four sensor references.
This is useful when designing a mold with different versions of the mechanical sensor because the designer does not need to create a completely different mechanical interface for each of these four references, based on the information contained in this drawing.
16. Why Vega Performed Additional Testing
The original email contains another important detail.
The Technical Department stated:
“The next week I will intensify the tests on the samples you sent me.”
This shows that the dimensional information was being supported by practical testing.
That is particularly relevant when dealing with mechanical switches.
A mechanical sensor is not just a theoretical dimension on a drawing.
Its real-world behavior depends on:
- contact geometry;
- switch mechanism;
- mechanical tolerances;
- repeated actuation;
- installation;
- the actual sample.
The technical process in this case therefore combined:
drawing + dimensional definition + physical testing.
17. Why Prototype Testing Is Valuable
When a customer develops a new mold, it can be useful to verify the actual mechanical interface before the final mold is manufactured.
A prototype can be used to verify:
- pin position;
- contact point;
- switching position;
- mechanical travel;
- repeatability;
- cable routing;
- surrounding clearances.
The Case 153 correspondence shows Vega testing samples supplied by the customer specifically in connection with the mechanical sensor range.
This is a good engineering approach when the application has tight tolerances.
18. A Practical Design Procedure
For a new mold using a Vega mechanical switch, the following procedure can be used.
Step 1 — Identify the exact cylinder
Confirm:
- cylinder model;
- bore;
- stroke;
- cylinder version;
- mechanical-switch reference.
Do not assume that dimensions from one switch configuration automatically apply to another product.
Step 2 — Obtain the correct sensor drawing
Use the drawing corresponding to the actual sensor configuration.
For Case 153, the relevant drawing defines the operating range and the dimensions of the contact-pin arrangement.
Step 3 — Establish the pin’s open position
The Case 153 drawing specifies:
3.4 +0.1 / −0.1 mm
for the open contact-pin position.
This provides the reference for the mechanical design.
Step 4 — Identify the activation field
The drawing explicitly identifies the field in which the compressed pin must activate the microswitch.
This is the critical area that must be respected by the mold component.
Step 5 — Design the contacting component
The mold component that actuates the switch should be designed so that its movement brings the pin into the required activation field.
Step 6 — Account for tolerances
Consider the combined tolerances of:
- cylinder;
- switch;
- mold;
- moving component;
- mounting;
- assembly.
The worst-case position should remain within the required operating range.
Step 7 — Check the mechanical stop
Ensure that the moving component does not unnecessarily overload the contact pin after the microswitch has been activated.
Step 8 — Test the actual assembly
For critical applications, verify the actual switch behavior on the assembled components before finalizing the mold.
19. What the Designer Should Put on the Mold Drawing
When the switch is mechanically actuated by a mold component, the relevant dimensions should be clearly defined.
The drawing should ideally identify:
- switch reference;
- contact-pin position;
- activation position;
- mechanical stop;
- relevant tolerances;
- direction of movement;
- clearance around the switch.
This makes the interface between the cylinder supplier and mold builder much clearer.
20. Why a Generic “Switch Stroke” Value Can Be Misleading
A customer may ask:
“What is the stroke of the mechanical switch?”
This question may be too generic.
For a mechanical switch installed on a hydraulic cylinder, what matters in the application is not simply a single “stroke” value.
The designer needs to know:
- where the pin starts;
- how far it is compressed;
- where the microswitch changes state;
- the permitted operating field;
- how the external mold component interacts with the pin.
The Case 153 drawing is therefore more useful than a single generic number because it shows the actual mechanical operating geometry.
21. Mechanical Switches vs. Other Sensor Technologies
Vega currently offers different end-of-stroke technologies depending on the cylinder.
The product range includes:
- magnetic switches;
- inductive switches;
- mechanical switches.
The choice depends on the cylinder construction and application.
For example, Vega specifically explains that the all-steel body of the V450CM makes magnetic sensing unsuitable and therefore mechanical switches are used as a solution.
This is an important application principle:
The sensor technology must be selected according to the physical construction and operating conditions of the cylinder.
22. Mechanical Switches for High-Temperature Applications
Mechanical switches can also be advantageous in applications where temperature limits are important.
Vega’s current V450CM documentation states that cylinders equipped with mechanical switches can operate up to 180°C, while the corresponding inductive-switch configuration has a lower maximum working temperature.
The Vega mechanical-switch range currently includes:
- MS5 — 80°C;
- MS6 — 180°C;
- MS7 — 80°C with connector.
The exact switch and cylinder configuration must always be checked before applying these values to a specific project.
23. Do Not Apply Case 153 Dimensions to Every Vega Switch
This is an important limitation.
The dimensions in Case 153 belong to the specific technical drawing supplied in that case.
The drawing identifies the sensor references MSA, MSB, MSC and MSD and states that the shown values are identical for those sensors.
Therefore, we should not automatically assume that the 3.4 mm, 0.5 mm and 0.8 mm dimensions apply to every mechanical switch currently offered by Vega.
For a new customer application, the correct procedure is:
Check the drawing for the exact cylinder and switch configuration.
This is particularly important because Vega’s current product range contains different mechanical-switch families and configurations.
24. A Useful Rule for Future Customer Questions
If a customer asks:
“How much should we compress the mechanical switch pin?”
we should not answer with a generic value unless we have confirmed the exact sensor configuration.
Instead:
- identify the cylinder;
- identify the switch;
- check the relevant drawing;
- identify the open-pin position;
- identify the activation field;
- check the customer’s mechanical tolerances;
- confirm the final installation.
For Case 153, the drawing provides the specific dimensional information required for this process.
25. Recommended Response to a Customer
For a customer asking about the mechanical switch operating range, a technically appropriate response based on this case would be:
The operating position of the mechanical switch must be defined according to the sensor drawing rather than by the hydraulic-cylinder stroke alone. For the sensor configuration shown in the attached Vega drawing, the contact pin has an open position of 3.4 mm with a +0.1 / −0.1 mm tolerance. The drawing also identifies the specific field in which the compressed pin must activate the microswitch.
Please ensure that the mold component actuating the switch brings the contact pin within this operating field and that the mechanical tolerances of the complete assembly are taken into account. If you provide us with the cylinder/sensor reference and your mold drawing, our Technical Team can verify the installation.
This is preferable to giving a generic “switch stroke” number.
26. The Main Lesson from Case 153
The key lesson is:
A mechanical end-of-stroke switch should be designed as a precise mechanical interface, not simply as an electrical accessory attached to a hydraulic cylinder.
The Case 153 drawing provides:
- the contact-pin reference position;
- the dimensional tolerance;
- the activation field;
- the applicable sensor references.
The corresponding technical email confirms that the drawing was specifically prepared to define the mechanical sensor’s working range and that additional tests were planned on customer-supplied samples.
For mold designers, the practical message is simple:
Do not design only around the cylinder stroke.
Design around the complete mechanical switching interface.
27. Conclusion
Mechanical switches are a practical solution for detecting hydraulic-cylinder position, particularly in applications where magnetic sensing is unsuitable or where compact mechanical integration is required. Vega currently offers several mechanical-switch configurations for its hydraulic-cylinder range.
However, correct operation depends on the mechanical relationship between the switch pin and the component that actuates it.
Case 153 provides a clear example.
The Vega drawing specifies an open contact-pin position of:
3.4 +0.1 / −0.1 mm
and identifies the field in which the compressed pin must activate the microswitch. It also states that the dimensional values shown apply to sensors MSA, MSB, MSC and MSD.
The corresponding Technical Department email confirms that the drawing was supplied specifically to define the mechanical sensor’s operating range and that additional testing was planned using samples supplied by the customer.
The most important engineering principle is therefore:
The mold designer must control the position and compression of the mechanical switch pin so that the microswitch is activated within the specified operating field, while accounting for the tolerances of the complete mechanical assembly.
For any new application, the exact cylinder and sensor reference should be verified before applying dimensional values from an older technical case.
Useful Vega References
- Vega Mechanical End-Stroke Switches — official Vega page explaining the mechanical-switch range and its applications.
- Vega End-Stroke Switches for Hydraulic Cylinders — official overview of magnetic, inductive and mechanical end-of-stroke switches.
- Vega MS5 Mechanical Switch — official MS5 product page for V450CM cylinders.
- Vega V450CM Compact Hydraulic Cylinders — official cylinder page with information about mechanical and inductive switch configurations.
- Vega V215CD Hydraulic Cylinders with Mechanical and Other Sensors — official example of mechanical, inductive, magnetic and encoder sensing options.
