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For large part assembly requiring high throughput, linear vibration welding is a widely used joining technology for thermoplastic parts. During vibration welding, one part half is held stationary in a holding fixture while the other part half is frictionally vibrated against it on a linear plane at 150-250Hz under carefully controlled pressure, creating frictional heat at the joining surfaces. Forward has been designing and building vibration welding systems since 1990. Our large upper tool weight capability makes our welders unique in their class. Unsurpassed control is achieved through the use of eight adjustable amplitude, time (optional collapse/absolute distance) and force steps. Four standard sizes are available, each equipped with our Patented Advanced 2-Pole Digital Servo Drive, making them the most advanced and powerful welders on the market today. Forward Technology's vibration welders are complete plastic assembly systems specifically designed to weld a variety of part sizes and geometries. They are also compatible with many thermoplastic materials. Linear Vibration Welding Process Advantages
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About Linear Vibration Welding
Advanced 2-Pole Digital Servo Drive Vibration System
Designing for Linear Vibration Welding
Vibration Weld Tooling
Vibration vs. Other Welding Methods
About Linear Vibration Welding
Linear Vibration Welding is a frictional welding technique capable of producing strong, air-tight welds in thermoplastic parts.
In this process, vibration occurs by transverse reciprocating motion controlled electro-magnetically by a swing frame assembly containing precision springs, electromagnets and an electromagnetic drive assembly which controls the amplitude and frequency of the vibrating head.
Friction is achieved through motion between two parts, one fixed, the other reciprocating at a controlled amplitude and frequency while clamped under pressure. Melt occurs only at the interface of the joint area of the plastic part halves.
Linear Vibration Welding Process:
STEP 1Part halves are placed into and securely gripped by precision holding fixtures which insure adequate support and accurate alignment of the part halves throughout the vibration welding process.
STEP4Vibration halts and the holding fixtures maintain clamping force, allowing the parts to cool under pressure.
| STEP2The lower holding fixture rises upward to close against the upper holding fixture, compressing the part halves to be welded together.
STEP 3Friction (heat) begins by vibration controlled by alternate energizing of electromagnets on the swing frame assembly. This pulsation propels the vibrating platen and the upper tooling fixture alternately left and right, generating a peak to peak movement of up to 0.070 inches.
STEP 5When cooling is complete, the lower fixture lowers and the finished part may be unloaded.
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Our existing line of vibration welders includes four unique sized models. Hydraulic and pneumatic versions are available. From manually loaded and unloaded machines to semi and fully automated in-line systems, each of our vibration welders is designed to accommodate a specific range of application requirements.
Critical Vibration Welder Parameters:
- Frequency
- Amplitude
- Weld Force
- Weld Collapse/Absolute Distance
- Weld Time
- Hold/Cool Time
- Hold/Cool Force
Linear Vibration Welding Melt Phases:
- Phase 1 – Heat is generated at the parts joint surface. No melting has started at this point.
- Phase 2 – Melt-down (displacement) initiates as frictional heat is created.
- Phase 3 – Material surface is melted and approaches consistent melt-down across joint.
- Phase 4 – Hold time for polymer cooling.
Back to topAdvanced 2-Pole Digital Servo Drive Vibration System
Forward's Advanced 2-Pole Digital Servo Drive Vibration system patented. To learn more about Forward Technology's patents click here.
The Advanced 2-Pole Digital Servo Drive Linear Vibration Welder is one of our latest breakthroughs in thermoplastic welding technology.
Continuous developmental efforts to advance Vibration Welding technology have led to the new 2-Pole Digital Drive System. This patented technology allows vastly improved process control while substantially increasing the available power. The newly designed drive was developed from many years of experience and was the next logical step to improving the maintenance-free electromagnetic vibration head. This technology offers improvements in overall efficiency (significant power increase), capability (amplitude/process control) and productivity (application benefits) beyond any vibration welding design currently on the market.
Significant Power Increase
Each magnet in the new drive is driven by an independent amplifier to allow for maximum efficiency. This ensures no overlap of applied magnetic fields, as typically seen in traditional 3-Pole vibration welding drives. An industrial high-speed processor controlsthis process. As a result, power is increased significantly over traditional 3-Pole systems.
The Automatic Frequency Resonant Control(AFRC) of the new vibration welder allows continuous tuning throughout the welding step (no longer requiring auto-tuning as a time consuming setup-step). The system will adjust the frequency constantly during each weld depending on tool weight and part conditions. Optimal power is being delivered to the part throughout the welding cycle.
The new system also allows for higher flexibility on several variables:
- Frequency ranges from 180 to240 Hz
- Clamp force up to 8000 lbs.
- Possible upper tooling weight range from 40 - 105kg
Amplitude/Process Control
The ultra high-speed processor monitors for over-travel every 0.00022 seconds resulting in approximately 18 check points on each amplitude wave in a 250Hz system. Due to the high efficiency and accuracy of the amplitude control, full amplitude can be in as low as 0.032 seconds. Traditional systems are working between 0.3 and 1 seconds depending upon the application.
Features like profiling of amplitude and pressure, as well as multiple weld modes (welding and/or setting process control limits by: Time, Collapse Distance or Absolute Distance) are part of the optimized weld controls.
Data communication ports can be integrated and used to connect the welder to a customer's computer station for data acquisition and SPC purposes.
Application Benefits
As compared to traditional 3-Pole drive vibration welders, the new digital drive system re-defines the process phases of vibration welding. The following graphs were taken while welding the identical parts utilizing the same tooling first on a traditional 3-Pole drive vibration welder followed by a welder equipped with our Advanced 2-Pole Digital Drive system.
| Earlier 3-Pole Vibration WeldingTechnology | Advanced 2-Pole DigitalVibration Welding Technology |
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- In the example above, complete weld time on the same parts went from approximately 7 seconds down to 4 seconds.
- Melt phases are drastically reduced due to reaching the optimal amplitude a ta much faster rate and the high power efficiency of the welder.
In some applications using this system, there has been a significant reduction in the amount of flash produced during the vibration process. This reduction is due to the fast melting times in the melt phases of the vibration welding process. The flash, in some cases, actually resembles a part welded by using the hot plate welding process.
Designing for Linear Vibration Welding
Linear Vibration Weld Strength:
The linear vibration welding process produces a welded joint which, in many cases, yields a weld strength that is consistently equal to or stronger than any other area of the part. As a result, the weld area can most often be exposed to the same strains and stresses as any other area of the part.
Common Vibration Welded Materials:
- Acrylonitrile Butadiene Styrene (ABS-Cycolac)
- Acrylic-Styrene-Acrylonitrile (ASA-Geloy)
- Cellulose Acetate (CA)
- Cellulose Acetate Butyrate (CAB)
- Cellulose Acetate Propionate, (CAP)
- PolyOxy-Methylene (POM-Acetal & Delrin)
- PolyAmide (PA-Nylon & Zytel)
- PolyButylene Terephthalate (PBT-Valox & Enduran)
- PolyCarbonate (PC-Lexan & Makrolon)
- PolyCarbonate / Acrylonitrile- Butadiene- Styrene (PC/ABS-Cycoloy & Bayblend)
- PolyCarbonate/ PolyButylene Terphthalate (PC/PBT-Xenoy)
- PolyCarbonate/ PolyEthylene Terephthalate (PC/PET-Xylex & Makroblend)
- PolyEthylene (PE)
- PolyEthylene Terephthalate (PET-Polyester)
- PolyMethyl MethAcrylate (PMMA-Acrylic & Lucite)
- PolyMethylPentene (PMP-TPX)
- PolyPhenylene Oxide (PPO-Noryl)
- PolyPhenylene Sulfide (PPS-Ryton)
- PolyPropylene (PP)
- PolyStyrene (PS)
- PolySulfone (PSO-Udel)
- PolyVinyl Chloride (PVC-Vinyl)
- PolyVinylidene Fluoride (PVDF-Kynar)
Vibration Welding Joint Design:
Joint design varies with each application and depends onfactors such as type of plastic to be welded, part geometry andrequirements of the weld. We recommend discussing joint designs withone of our application engineers before arriving at your final partdesign.
Other Vibration Welding Design Considerations:
- Ideal parting line will be parallel to the force applied by the lift table.
- Joint design must allow for sufficient collapse distance, insufficient collapse may cause poor weld strength/quality.
- Joint and part clearance should allow for at least .100” linear movement between part halves.
- Joint contours of more than 10 degrees parallel to the direction/axis of vibration will most often not produce welds of sufficient strength.
- Parts must be rigid, flexibility in the part will result in poor welding.
- Tall internal walls perpendicular to direction of vibration must be stiffened or they will not weld.
Vibration Weld Tooling
Advantages of Forward Technology Vibration Tooling:
- Over 95% of all tooling is designed and manufactured for your application by our in-house Tooling Design and Fabrication department in Cokato, MN.
- This in-house capability insures optimal quality and scheduling control as well as reducing time requirements in the event of product design changes.
- No charge/obligation complete application review and joint design assistance.
- Full prototyping capability.
- All tools are designed for ease of maintenance, adjustment, and maximum life.
- Tools provide support and location of joint area as well as accurate alignment throughout the welding process.
- Virtually every tool are thoroughly tested and debugged at our facility on equipment in our laboratory.
- Tools can be designed for use with Forward Technology or competitors welders.
- Full start-up service/support at your facility is available.
Standard Vibration Tooling:
- Precision CNC cut holding fixtures supports joint area of each part half.
- Holding fixtures can be split if necessary to accommodate part-to-part variations or for welding warm/hot parts.
- Hardened steel knurled gripping sections.
- Steel, aluminum, titanium materials used for maximum rigidity.
- Lightweight aluminum backing plates
- Locator stop-posts to reduce tooling change-over time and prevent tooling crashes (in the event operator cycles without parts).
- Heavy-duty slides for support & part retention in areas where clearance is needed for loading & unloading on lower tooling.
- Custom slides for inspections & part detection.
Cast Urethane Vibration Tooling:
- The holding fixture foundation is a ¼” to 3/8” CNC cut aluminum translation of the actual part based on CAD data.
- A production quality part is then placed into the CNC machined aluminum holding fixture (spaced ¼ to 3/8” from the part).
- Urethane skin is poured to the contour of the part.
- Cast Urethane will protect and locate Class-A surfaces.
Vibration Tooling Options:
- Part Presence Sensors verify part presence/position prior to allowing machine to cycle.
- Part Eject eases removal of welded parts from tooling.
- Anti-Static Guns remove static buildup from parts.
- Vacuum Cleaning reduces amount of particulate around the welded parts.
- Quick Change System for customers using multiple tools in one machine.
Vibration vs. Other Welding Methods
Vibration vs. Infrared Welding
VIBRATION WELDING | INFRARED WELDING |
Faster cycle times:
| Slower cycle times:
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| Cannot weld tall, thin, non-supported either: a) inside walls or b) outside walls perpendicular to the direction of vibration. | Can weld tall, thin, non-supported inside and outside walls. |
| Process works well for a variety of applications (some limitations). | Process works well for a variety of materials (few limitations). |
| Can be difficult to weld VERY large parts. | Almost no part size limitations. |
| Lower joint strength with Polypropylene and Polyethylene due to absorption of vibration within the material instead of transfer to the joint area. | Higher joint strength with Polypropylene and Polyethylene as the process heats the interface without friction. |
| Process can join certain dissimilar materials (limited number). | Process can join certain dissimilar materials (limited number). |
| Can weld parts with contours in one direction only. | Can weld parts with contours in both directions. |
| Weld plane limited to 10° maximum from flat in the axis parallel to vibration. | Weld plane limited to 45° maximum from flat plane. |
| Lower tooling costs (no infrared platen required). | Higher tooling costs (requires infrared platen). |
| Less complex tooling. | Process requires an infrared platen assembly. |
| Lower tooling maintenance. | Infrared platen maintenance; periodic replacement of infrared emitters required. |
| Faster tooling change-over times. No platen to change. | Slower tooling change-over times; may have to change infrared platen. |
| Process can create flash that can break off causing loose particles (application and material dependant). | Process creates solid, smooth flash bead with virtually no particulate. |
| Virtually no smoke or fumes during welding process. | Process most often will create smoke and fumes. |
Vibration Welding vs. Hot Plate Welding
VIBRATION WELDING | HOT PLATE WELDING |
Faster cycle times:
| Slower cycle times:
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| Cannot weld tall, thin, non-supported either: a) inside walls or b) outside walls perpendicular to the direction of vibration. | Can weld tall, thin, non-supported inside and outside walls. |
| No direct control of temperature at weld joint. | Direct control of temperature at weld joint. |
| Process works well for a variety of applications (some limitations). | Process works well for a variety of materials (few limitations). |
| Easy welding of Nylon. | Complex to weld Nylon. Involves ultra high-temperature heat platen cores which must be scrubbed with metal brushes every cycle to clean off build-up of residual material. Yields the strongest bonds compared to most other welding methods. |
| Can be difficult to weld VERY large parts. | Almost no part size limitations. |
| Lower joint strength with Polypropylene and Polyethylene due to absorption of vibration within the material instead of transfer to the joint area. | Higher joint strength with Polypropylene and Polyethylene as the process heats the interface without friction. |
| Fillers in the material are not a problem. | Fillers in the material can build up on the heat platen requiring periodic cleaning (automatic cleaning systems are available on certain models). |
| Process can join certain dissimilar materials (limited number). | Process can join certain dissimilar materials (limited number). |
| Can weld parts with contours in one direction only. | Can weld parts with contours in both directions. |
| Weld plane limited to 10° maximum from flat in the axis parallel to vibration. | Weld plane limited to 45° maximum from flat plane. |
| More sensitive to molded part variations. | Less sensitive to molded part variations. |
| Higher initial capital equipment costs. | Lower initial capital equipment costs. |
| Lower tooling costs (no heat platen required). | Higher tooling costs (requires heat platen). |
| Less complex tooling. | Process requires a heat platen assembly. |
| Lower tooling maintenance. | Heat platen maintenance; replace heaters and Teflon inserts when using low temperature. |
| Faster tooling change-over times. | Slower tooling change-over times; also may have to change heat platen and allow for heat up. |
| Process can create flash that can break off causing loose particles (application and material dependant). | Process creates solid, smooth flash bead with virtually no particulate. |
| Virtually no smoke or fumes during welding process. | Virtually no smoke or fumes during welding process at low temp; will create smoke and fumes when welding at high temp. |
| Lower power consumption (no heat platen heaters). | Higher power consumption (required for heaters). |
Forward Technology is a Crest Group Company