A Real Vega Technical Case About Cable Bending and Magnetic Interference
When a hydraulic cylinder is installed inside an injection mold, the available space is often extremely limited.
A few millimeters can make the difference between a correctly installed switch and a switch that does not operate reliably.
This is especially true when a hydraulic cylinder is equipped with mechanical end-of-stroke switches and the switch cable must be routed through a narrow space between the cylinder and the surrounding steel components of the mold.
A real Vega technical case from June 2015 provides a useful reference for this situation. The customer asked how much space had to be left around the switch cable because only 10 mm was available and there was concern that excessive cable bending could affect the operation of the switch.
The technical answer identified two separate dimensional requirements that must not be confused:
- approximately 10 mm minimum space for bending the cable, with 15 mm preferable;
- at least 25 mm between the cylinder and the surrounding steel mass to ensure correct operation of the switch.
This distinction is extremely important when designing compact mold installations.
1. The Customer’s Question
The original request was very practical.
The customer had a cylinder installed completely inside the mold and wanted to know how much space should be left for the switch cable.
The available space was approximately 10 mm.
The concern was that the cable might have to bend too sharply and that this could prevent the switch from operating correctly.
This is a typical problem in compact mold design.
The cylinder itself may fit perfectly into the available cavity, but the switch and cable require additional installation space.
Therefore, when a cylinder is selected, it is not sufficient to consider only the external dimensions of the cylinder body.
The switch installation must also be considered.
2. The First Requirement: Cable-Bending Space
The Vega technical response specified:
The minimum space to bend the cable is about 10 mm, with 15 mm being preferable.
This provides a practical design reference.
If the available space is approximately 10 mm, the installation is at the minimum recommended limit.
If approximately 15 mm can be provided, the cable has a more favorable routing condition.
This means that the difference between:
10 mm
and
15 mm
may be important during mold design.
3. Why Cable Routing Matters
A switch cable is not simply an electrical connection that can be bent arbitrarily.
The cable must be routed without creating excessive mechanical stress.
An installation with insufficient space can result in:
- excessive bending;
- mechanical stress at the cable exit;
- an overly tight bend radius;
- difficulty during assembly;
- difficulty during maintenance;
- possible long-term damage to the cable.
For this reason, the designer should consider the cable routing before finalizing the mold geometry.
The goal should not simply be to make the cable “fit.”
The goal should be to provide enough space for a practical and reliable installation.
4. 10 mm Is a Minimum, Not the Preferred Design Condition
The wording of the original Vega response is important.
It does not say that 10 mm is the ideal clearance.
It states that:
- approximately 10 mm is the minimum;
- approximately 15 mm is preferable.
Therefore, when designing a new mold, the recommended approach is:
If possible:
Design for approximately 15 mm.
If space is extremely restricted:
Do not go below approximately 10 mm without checking the specific installation.
This distinction is useful because mold designers frequently work with extremely small clearances and may interpret a minimum dimension as an ideal dimension.
5. But There Is Another, More Important, 25 mm Requirement
The most interesting part of this technical case is that the cable clearance is not the only dimensional requirement.
After reviewing the customer’s drawing, the Vega Technical Team noticed that the entire cylinder was located inside the mold.
The response therefore highlighted another critical point:
the customer needed to verify the minimum distance between the cylinder and the surrounding steel mass.
The required distance was:
25 mm minimum.
If the distance between the cylinder and the steel mass was less than 25 mm, the switch could not work correctly.
This requirement is completely different from the cable-bending clearance.
6. Two Different Clearances Must Be Considered
This case therefore gives us two separate design rules.
| Requirement | Minimum / Recommended Space |
|---|---|
| Space for bending the switch cable | 10 mm minimum |
| Preferred cable-bending space | 15 mm |
| Distance between cylinder and steel mass | 25 mm minimum |
These dimensions have different purposes.
10–15 mm
This concerns physical cable routing.
25 mm
This concerns the correct operation of the switch in relation to surrounding steel material.
Confusing these two dimensions could lead to an incorrect mold design.
7. Why Can Surrounding Steel Affect the Switch?
The 25 mm requirement is particularly important because the switch operation is influenced by the surrounding geometry.
The original Vega technical response specifically states that if the distance between the cylinder and the steel mass is below 25 mm, the switch may not work correctly.
Therefore, the designer cannot simply ask:
“Does the cylinder fit?”
The correct question is:
“Does the cylinder fit while maintaining the required clearance for correct switch operation?”
This is a much more important design consideration.
8. The Cylinder Can Fit While the Switch Still Does Not Work Correctly
This is one of the most useful lessons from the case.
Imagine that the mold cavity has been designed around the external dimensions of the hydraulic cylinder.
The cylinder fits.
The mounting holes are correct.
The hydraulic connections are accessible.
Everything appears to be fine.
However, if a large steel mass is positioned too close to the cylinder, the switch may not operate correctly.
Therefore:
Mechanical cylinder clearance ≠ switch operating clearance.
The switch must be considered as part of the overall installation.
9. Why This Is Particularly Important Inside Injection Molds
Injection molds frequently have:
- limited installation space;
- thick steel plates;
- moving cores;
- slides;
- ejector systems;
- hot-runner components;
- hydraulic cylinders;
- sensors and switches.
The available space around a cylinder can therefore be very small.
Vega hydraulic cylinders are specifically designed for applications in plastic injection and die-casting molds, where compact dimensions and integration with the mold are important design factors.
For this reason, the installation of a cylinder with switches should be considered during the mold-design stage rather than after the mold has already been manufactured.
10. The Switch Is Part of the Installation Envelope
When selecting a cylinder, engineers often look at the cylinder’s:
- bore;
- stroke;
- overall length;
- mounting dimensions;
- rod diameter.
But when a switch is installed, the switch and its cable become part of the installation envelope.
The available space must therefore be checked around:
cylinder + switch + cable + surrounding mold steel
rather than around the cylinder body alone.
This is particularly important when the cylinder is completely enclosed by the mold.
11. A Practical Design Example
Consider a cylinder installed inside a mold.
Suppose the designer has:
10 mm of space available for the cable.
According to the Vega technical response, this is approximately the minimum space required to bend the cable.
However, the designer must then check another dimension.
If the cylinder is only:
15 mm from a surrounding steel mass
the installation does not satisfy the 25 mm requirement identified by Vega for correct switch operation.
Therefore, having sufficient space for the cable does not automatically mean that the switch installation is correct.
12. The 25 mm Dimension Should Be Checked During Mold Design
The distance between the cylinder and the surrounding steel mass should be checked directly on the mold drawing.
The designer should identify:
- cylinder outer dimensions;
- switch position;
- steel plates;
- inserts;
- cores;
- moving components;
- fixed components;
- available clearances.
The relevant distance should then be verified in the actual installation condition.
The original Vega technical response specifically referred to the drawing supplied by the customer and recommended checking this dimension against the 25 mm minimum indicated in the catalog.
This is a good example of why technical support should review the customer’s drawing rather than answer only from a generic product dimension.
13. Do Not Look Only at the Cylinder Catalog Dimension
A catalog can tell you the external dimensions of a hydraulic cylinder.
But the catalog alone may not tell you whether the customer’s particular mold geometry will allow the switch to operate correctly.
The installation must be evaluated in context.
This is particularly true when:
- the cylinder is completely enclosed;
- steel components are very close;
- the switch is installed near a mold plate;
- cable routing is restricted;
- several cylinders are installed close together.
Vega’s current product range includes hydraulic cylinders with mechanical switches as well as cylinders available without switches, depending on the configuration.
This means that the switch configuration should be considered at the same time as the cylinder configuration.
14. What Happens If There Is Not Enough Space?
If the mold design does not provide sufficient space, the problem should be identified before manufacturing whenever possible.
Possible actions depend on the exact application and should not be assumed without checking the specific cylinder and switch configuration.
The design team may need to evaluate:
- changing the switch arrangement;
- modifying the cable routing;
- increasing the available clearance;
- using a different cylinder configuration;
- using a cylinder without switches if position detection is not required;
- modifying the mold geometry.
The important point is that the correct solution must be selected from the actual installation conditions.
15. Cable Clearance and Steel Clearance Are Independent Checks
A useful way to remember this case is to treat the two requirements as separate checks.
Check A — Cable routing
Ask:
Is there enough space to bend and route the switch cable?
Reference from the Vega case:
10 mm minimum, 15 mm preferable.
Check B — Switch environment
Ask:
Is there enough distance between the cylinder and the surrounding steel mass for the switch to operate correctly?
Reference from the Vega case:
25 mm minimum.
These checks should be performed independently.
16. Why Reviewing the Customer’s Drawing Is So Important
The original customer did not simply ask a theoretical question.
The customer provided a drawing showing the actual cylinder installation inside the mold.
This allowed the Vega Technical Team to identify a potential problem that went beyond the original question about cable bending.
The customer was worried about:
10 mm of cable space.
The Technical Team identified another potential issue:
the distance between the cylinder and the surrounding steel mass.
This is a good example of effective technical support.
A strong technical answer should not only answer the question that was asked.
It should also identify related installation conditions that could affect the correct operation of the product.
17. The Role of the Technical Team
The case also demonstrates the value of technical support in hydraulic-cylinder applications.
The Technical Team did not simply respond:
“10 mm is okay.”
Instead, the drawing was reviewed and another requirement was identified.
The final answer was essentially:
- 10 mm is approximately the minimum cable-bending space;
- 15 mm is preferable;
- but the customer must also check the 25 mm minimum distance from the surrounding steel mass because otherwise the switch may not work correctly.
This is the type of response that prevents an installation problem from appearing after the mold has already been manufactured.
18. A Step-by-Step Installation Check
For future mold designs, the following procedure can be used.
Step 1 — Identify the cylinder configuration
Confirm:
- cylinder model;
- bore;
- stroke;
- mounting configuration;
- switch type.
Step 2 — Locate the switch
Determine exactly where the switch is positioned relative to the cylinder body and mold.
Step 3 — Check cable space
Provide approximately:
10 mm minimum
and preferably:
15 mm
for cable bending.
Step 4 — Check the surrounding steel
Measure the distance between the cylinder and nearby steel masses.
The Vega case specifies:
25 mm minimum.
Step 5 — Check the complete 3D envelope
Verify:
- switch;
- cable;
- fittings;
- hoses;
- mold plates;
- moving parts.
Step 6 — Check accessibility
Make sure the switch and cable can be installed and serviced.
Step 7 — Validate before machining the mold
If the clearance is uncertain, send the mold drawing to Vega Technical Support for review before final machining.
19. A Small Clearance Can Become a Major Problem
In mold engineering, a difference of only a few millimeters can have a significant impact.
A mold may already be:
- machined;
- assembled;
- polished;
- tested;
- ready for production.
Discovering at this stage that the switch cable cannot be routed correctly or that the surrounding steel is too close can lead to:
- re-machining;
- delays;
- additional costs;
- replacement components;
- production downtime.
For this reason, the installation clearance should be treated as a design parameter, not as an assembly detail.
20. Mechanical Switches Must Be Considered as Part of the Cylinder System
A hydraulic cylinder equipped with a mechanical switch is not simply:
cylinder + optional accessory.
For the purpose of installation design, it is:
cylinder + switch + cable + surrounding environment.
This is especially important when the cylinder is installed inside a mold.
Vega’s current product information confirms that mechanical switches are available for its hydraulic-cylinder range and that different switch technologies are used depending on the cylinder and application.
Therefore, the designer should select the switch configuration at the same time as the hydraulic cylinder rather than treating it as an afterthought.
21. What Should We Ask a Customer Who Has Limited Space?
If a customer says:
“We only have 10 mm available around the switch cable. Is that enough?”
we should not answer only:
“Yes.”
The correct response should also remind the customer to check the surrounding steel clearance.
A useful technical response would be:
Approximately 10 mm is the minimum space required to bend the switch cable, while approximately 15 mm is preferable. In addition, please check the distance between the cylinder and the surrounding steel mass. According to the Vega catalog, a minimum distance of 25 mm is required for correct switch operation. If the distance is less than 25 mm, the switch may not operate correctly.
This reproduces the substance of the original Vega technical response.
22. The Key Lesson From This Technical Case
The most important lesson is:
The installation space required by a hydraulic cylinder with a switch is not determined only by the cylinder dimensions.
There are at least two additional considerations highlighted by this case:
Cable routing
→ approximately 10 mm minimum, 15 mm preferable.
Distance from surrounding steel mass
→ at least 25 mm for correct switch operation.
Therefore, a mold designer should never approve a cylinder installation simply because the cylinder body fits into the available cavity.
The complete switch installation must also be checked.
23. Conclusion
This real Vega technical case began with a simple question:
How much space is required for the switch cable?
The customer had only approximately 10 mm available and was concerned that excessive cable bending could affect switch operation.
The Vega Technical Team clarified that approximately 10 mm is the minimum space required to bend the cable, while 15 mm is preferable.
However, reviewing the customer’s drawing revealed a second and potentially more important requirement: because the cylinder was completely enclosed inside the mold, the distance between the cylinder and the surrounding steel mass also had to be checked.
If that distance is less than 25 mm, the switch may not operate correctly.
The case therefore teaches a simple but important design principle:
When installing a hydraulic cylinder with a switch inside a mold, check not only whether the cylinder fits, but also whether the switch has enough space to operate correctly and whether the cable can be routed without excessive bending.
For future applications, the two reference dimensions from this case should be remembered:
10 mm minimum / 15 mm preferable for cable bending
and
25 mm minimum distance from the surrounding steel mass for correct switch operation.
These checks should be made during mold design, before the mold is machined, rather than after assembly.
Useful Vega References
- Vega Cylinders – Hydraulic Cylinders for Injection Molds — overview of Vega’s hydraulic-cylinder range for plastic injection molding and die casting.
- Vega V215CD – Hydraulic Cylinders with Mechanical and Inductive Sensors — product information showing the availability of mechanical switches and other sensor configurations.
- Vega Hydraulic Cylinder Products — complete product-category overview.
- Vega Materials and Components — technical information about cylinder construction and components.
