teamextruder_project_plan_document_final

Composites Extruder Head Development

Colin Biery (720)216-‐7625 [email protected] Ryan Dunn (303)229-‐8358 [email protected] Michael Hansen (720)427-‐1687 [email protected] Logan Rutt (303)495-‐8382 [email protected] Tristan Vesely (925)876-‐2343 [email protected]

Colorado State University, Mechanical Engineering,

Senior Practicum Projects Program

October 6, 2015

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____________________________ Advisor: Dr. Don Radford


Table of Contents Introduction ................................................................................................................................................... 2 Background .................................................................................................................................................... 2 Composites Properties .......................................................................................................................... 2 Composites Manufacturing ................................................................................................................. 3 Additive Manufacturing ........................................................................................................................ 3 Current Solutions .................................................................................................................................... 4

Problem Statement ..................................................................................................................................... 5 Goals ................................................................................................................................................................. 6 Design Constraints ....................................................................................................................................... 7 Work Plan and Design Evaluation .......................................................................................................... 7 Design Evaluation ..................................................................................................................................... 11 Management Plan .................................................................................................................................... 11 Meeting times ....................................................................................................................................... 11 Timeline and Milestones ................................................................................................................... 13

Concluding Statement ............................................................................................................................. 14 Budget Breakdown ................................................................................................................................... 14 References ................................................................................................................................................... 15


Introduction Fiber reinforced thermoplastic composites are incredibly useful materials due to

their impressive specific stiffness as well as their specific strength. Specific stiffness is measured by Modulus of Elasticity divided by density, and specific strength is measured by tensile strength divided by density. Unfortunately, composite manufacturing is a difficult and costly process that makes the practicality of composite parts unsuitable for many designs. In contrast additive manufacturing is a relatively simple manufacturing processes, but creates weaker parts. Combining the ease of additive manufacturing techniques with the strength of composites would enable designers to rapidly create components that meet structural requirements. This will eliminate lag time for prototypes and reduce market-‐level manufacturing times. The proposed solution to this challenge is a hot end extruder head capable of manufacturing consolidated thermoplastic composites through 3D printing. Advancement of composite materials in engineering design strongly depends on the availability of new manufacturing processes [7].

Background

Composites Properties Composite materials offer mechanical properties for engineering applications

that traditional materials cannot compete with. Their high specific strength can provide the same capabilities as high-‐grade aluminum at five to ten times less weight [2]. Additionally they have remarkable durability and resistance to fatigue [2]. Thermoplastic fiber composites function by transmitting external energy through the thermoplastic matrix material to the hard, brittle fiber reinforcements within. The fibers take the applied load

while the matrix protects them from damage. Properties of composites heavily depend on the properties of the matrix, reinforcement, and the ratio of matrix to reinforcement, which is traditionally stated as the percent weight of fiber [2,8].

Fiber orientation is one factor that determines the properties of a composite. As seen from Figure 1, there are several techniques for fiber and reinforcement placement. The most widely practiced fiber placement for composites is continuous and discontinuous (chopped) fiber [8]. Fibers are categorized by their aspect ratio (length divided by the diameter of the fiber), where continuous fibers have long aspect ratios and discontinuous fibers have short aspect ratios [1]. Composites are most effective when fibers are continuous and parallel, increasing their ultimate tensile strength and

Figure 1 -‐ Continuous vs. Short Fibers [11]


stiffness. Continuous fiber composites have anisotropic material characteristics, and fail at lower stress values when transversely loaded [2,8]. In contrast, Discontinuous short fiber composites tend to possess more isotropic material properties when compared to continuous fiber [2], but have lower tensile strength and Modulus of Elasticity.

Consolidation is an important issue when dealing with composite materials. Consolidation describes how effective the matrix/thermoplastic is at reaching and spreading between all of the fibers. Proper consolidation uniformly arranges the fiber reinforcement throughout the material with fiber volumes at 50% or above. One reason composites are advantageous over other materials is how the matrix distributes the external forces experienced by the composite to the stronger (and more brittle) fibers [5]. The transfer of energy between the matrix and fiber is accomplished through proper wetting of the composite. Proper wetting provides adequate bonding between the matrix and fibers, and transfers loads through shear to the fibers [2]. With inadequate wetting out of the fiber composite, the structural strength decreases and does not provide proper mechanical properties for engineering use. Without the stiff, brittle fibers the thermoplastic alone is far weaker and has a lower modulus of elasticity, because the matrix has lower tensile/compression strength and modulus of elasticity than the fibers. Without proper consolidation and wetting of the fibers, these material advantages can be lost. If the fibers are not distributed evenly through the thermoplastic matrix and not adequately transferring energy, you do not achieve consistent material properties throughout the composite.

Composites Manufacturing Although composites provide strong and stiff engineering materials, the

manufacturing process can be costly and time consuming. Manufacturability is a limiting factor for commercialization of these materials, where the process involves multiple steps and require bulky molds [7]. The tooling required to create composite components are expensive to design and manufacture and do not offer adaptability for design changes. In addition to expensive tooling, the manufacturing process often requires human intervention [6]. With high labor necessities the price of production increases due to lack of automation, and exposes individuals to unhealthy work environments containing fumes and high temperatures.

Additive Manufacturing Additive manufacturing (AM) refers to the process of building 3-‐D objects by adding layer upon layer of material to create a complete part [10]. There are many different types of additive manufacturing, the most common and commercially available being Fused Deposition Modeling (FDM). FDM generally uses thermoplastic filament as the stock material. The filament is fed into a heated extrusion nozzle where it is melted and then extruded onto a base plate through a hot end extruder head. The rate at which the filament is extruded is dependent on the specified printing speed of the extruder head. The faster the printing speed, the faster the filament is extruded [10]. The extruder head and base plate move on a minimum of three axes to outline the geometry


of the part. Currently, most of these printers move in the x-‐y plane to create a layer and then move in the z-‐direction to begin printing the next layer.

FDM manufacturing requires no tooling or user interaction to create finished parts. Parts are built up directly on the base plate from the ground up. This is advantageous as it requires no tooling but disadvantageous because it is limited in what geometries at can build vertically. They are built up using G-‐code generated from 3D specific software. This software reads stereolithography (STL) files and generates the code directly from them. This form of AM is extremely useful for developing geometries, however it is disadvantaged when developing structural properties for application purposes.

Current Solutions There are a few current ways that composites are being implemented into AM. These include using hot end extruder heads to pull and consolidate fibers, use plastic filament pre-‐impregnated with chopped fibers, and using printing plastics and fibers in series using multiple extruder heads.

A laboratory scale extruder head, developed by engineers in Zurich Switzerland, is capable of of processing continuous composite lattice structures [7]. The method of manufacturing is inspired by conventional 3D-‐printing, and uses a novel two-‐stage extrusion head to manufacture the composite as seen in Figure 2. This novel manufacturing method is currently patented for a continuous fiber lattice fabrication (CFLF).

CSU currently has two graduate students working with composite additive manufacturing. They are printing commingled tow, a form of composite stock material, onto a rotating mandrel using 3D extruder heads. This method requires tension on the stock material in order to achieve good consolidation.

There are multiple companies that are selling thermoplastic filament with short chopped fibers pre-‐impregnated into the filament. This composite filament can be

Figure 2 – Commingled tow extruder head developed by ETHZ Structures [7]


Figure 3 -‐ Mark Forged MarkOne Printer [3]

printed in many commercially available printers but does not add the desired benefit to properties that can be achieved from traditional composite manufacturing methods.

The only commercially available FDM printer that prints continuous fiber composites is the Mark One© by MarkForged [3]. It uses a dual head extruder system to print nylon out of one head and pre-‐preg fibers out of the other. This is called follow behind consolidation because the matrix is extruded on top of the fiber after extrusion. This method gives much higher strength values than a purely nylon part would achieving a tensile strength of 590 MPa for nylon-‐fiberglass composite [3].

Problem Statement

Composite material production is a time-‐intensive and expensive process when creating highly complicated parts. Tooling is difficult and must have a high level of precision to create quality parts. Molds created for a part are specific to that part, they cannot be used to manufacture anything else.

Fused deposition modeling is incredibly easy to use and can create unique shapes for virtually no overhead cost. It is versatile and capable, but the parts created are weaker than thermoplastic parts created with traditional methods. Being able to produce composite materials in unique shapes via additive manufacturing is an enabling technology opening up countless opportunities to save money by avoiding costly production techniques. Additive manufacturing is a rapidly growing field that keeps making breakthroughs in the potential it has. Composites are one of the few types of material, if not the only one left, that is not yet being printed. Research labs are already starting to experiment with this technology [7]. Before additive manufacturing of composites can become commercial there has to be a reliable foundation built in research labs. Researchers who make the most strides in composites extrusion stand to gain a great amount as many commercial companies will undoubtedly begin producing as many composites as possible this way. Ultimately those manufacturing composites stand to benefit from composites extrusion because they are paying the outstanding bill for current production methods. Currently Boeing® requires the use of carbon fiber thrust reversing cascade baskets for their jet engines. There is only one company in the


world which produces the baskets and they use an expensive hand-‐laying process. The proposed fused deposition modeling method of composite manufacturing has the potential of being a viable alternative to the current cascade manufacturing process.

Goals

The designated task is to design and build a progression of laboratory scale composite extruder heads capable of being mounted on a conventional or non-‐conventional 3D printer. The heads developed must successfully print fiber reinforced composite material. Each extruder head will be capable of printing composites with different stock material options:

● One head capable of using commingled tow and of wetting out dry continuous fiber.

● One head that is able to use lower cost forms of plastic feedstock than the commercial fused deposition plastic filament.

● One head capable of extruding continuous patterns of plastic and reinforcing dry fiber with plastic pellets as the feedstock.

● Print composites made up of a polypropylene thermoplastic matrix and glass reinforcing fibers in order to demonstrate capability of printing composites made up of a Peek thermoplastic matrix and carbon reinforcing fibers

Objectives Table 1 -‐ Design Objectives

Objective Name Priority* Method of Measurement

Objective Direction

Target

Consolidation 5 Photo Microscopy Maximize Evenly distributed fibers

Fiber Volume Fraction

4 Volume of fibers (cc)

Maximize 60%

Hot End Temperature Capability

3 Head temperature (degrees C)

Maximize 500°C

Operating Temperature

3 Head temperature (degrees C)

Optimize TBD via experimentation

Composites Stiffness 2 Specific Modulus (GPa)

Maximize 26.5 GPa [9]**

* Priority is weighed on 1-‐5 scale with 5 most important ** Value provided for 60% by volume glass fiber reinforced PP composite. Value will change based on material produced


Design Constraints

Table 2 -‐ Design Constraints Constraint Method of Measurement Limits

Material Stock Form Thermoplastics and Reinforcing Fibers Stock

Commingled tow, thermoplastic filament, dry fiber, thermoplastic pellets

Size Dimensions (mm x mm x mm) 54 x 65 x 65

Commercial Software Compatible slicing and controls software

Cura, Slic3r, etc.

Manufacturing Methods

Compatible types of additive manufacturing

Fused Deposition Modeling

Budget Dollars Spent $2000

Safety Possibility of Serious Injury 0

Work Plan and Design Evaluation

The work plan for our project is crucial to developing a successful product and will be executed in three iterative design and manufacturing processes, each of which are determined by the type of material stock to be extruded. These processes are broken down in detail in tables 3-‐5.


Table 3 -‐ 1st Extruder Head Iteration -‐ Commingled Tow Design Process Process step Task Breakdown (with number of hours allocated to

each task) 1. Acquire 3D FDM printer,

extruder head, and commingled tow Polypropylene (PP) Twintex stock material

• Develop printer criteria to be approved by Dr. Radford (3 hrs.)

• research and buy printer approved by Dr. Radford (8-‐10 hrs.)

• Communicate with Kent Warlick to receive PP Twintex material (1-‐2 hrs.)

2.) Attempt extruding commingled tow through original standard extruder head

• use small amount of PP Twintex in test extrusion of commingled tow using the original extruder head that was purchased with the printer (3 hrs.)

3.) Determine Procedure for effective pultrusion, consolidation, and extrusion of commingled tow with extruder head

• Meet with Kevin Hedin and Kent Warlick to determine current methods of tensioning, consolidating extruding, commingled tow on spinning mandrel printer (1-‐2 hrs.)

• identify and isolate most important components of extruder head for effective tensioning, consolidation, and extrusion (3-‐5 hrs.)

4.) Develop extrusion angle and flat plate printing techniques

• Use information acquired from initial testing and mandrel methods to generate concepts for tensioning consolidation and extrusion (10-‐15 hrs.)

5.) Design angled extruder head to consolidate and print Commingled tow

• Design mechanical components necessary to achieve goals determined in concept generation, using as much technology from prior commingled extrusion process as necessary ( 10-‐15 hrs.)

6.) Manufacture • Using the I2P lab and the team printer, print any parts necessary that are not temperature sensitive (printing time: 10-‐20 hrs.)

• Machine any temperature dependent components, either in house or professionally, depending on complexity of geometry (5-‐15 hrs.) (up to three weeks of lead time for professional manufacturing)

7.) Assemble and test extruder head • Test extruder head and parts printed based on current testing methods used by Kevin Hedin and Kent Warlick and previously found in research (15-‐20 hrs.)

8.) Revise design and modify extruder as necessary based on testing

• Based on testing, modify or redesign components of extruder head to increase composite print quality and use on 2nd and 3rd iteration of extruder head (5-‐20 hrs.)


Table 4 -‐ 2nd Iteration -‐ E-‐glass fiber tow and thermoplastic filament

Process step Task Breakdown (with number of hours allocated to each task)

1. Acquire E-‐glass Fiber feedstock and PP filament feedstock

• Purchase E-‐glass fiber tow feedstock (2-‐3 hrs) • Purchase PP thermoplastic filament feedstock (<1

hr)

2.) Modify 1st iteration of extruder head design to accommodate for thermoplastic filament feedstock.

• Generate concepts to accommodate for new feedstock material types (5-‐10 hrs)

• Modify designs of first iteration of head to be capable of tensioning consolidating, and extruding, composite as separate feedstocks; dry fiber and PP filament (14-‐18 hrs.)

3.) Manufacture new components of extruder head

• Print any parts necessary that are not temperature sensitive and were not previously manufactured from 1st iteration (printing time: 5-‐10hrs)

• Machine hot end extruder head, either in house or professionally, depending on complexity of geometry (5-‐15 hrs) (up to three weeks of lead time for professional manufacturing)

4.) Assemble and test • Test extruder head and parts printed based on current testing methods used by Kevin Hedin and Kent Warlick and previously found in research (15-‐20 hrs)


• Based on testing, modify or redesign components of extruder head to increase composite print quality used on 1st and to be used on 3rd iteration of extruder head (5-‐20 hrs)


Table 5 -‐ 3rd Iteration -‐ E-‐glass fiber tow and pellet stock Polypropylene feedstock Process step Task Breakdown (with number of hours allocated to each

task)

1.) Acquire matrix pellet feedstock

• purchase PP pellet stock, preferably premixed and ready to be used as is (1-‐3 hrs.)

2.) Develop compact process for melting and extruding pellet feedstock

• Working off of existing technology, develop a method to use thermoplastic feedstock that can be integrated into 3D printing process (8-‐12 hrs.)

3.) Modify 2nd iteration of extruder head design to incorporate pellet feedstock system

• Design components to use method developed to use pellet feedstock (10-‐15 hrs.)

• Modify designs to be capable of dealing with the addition of components for pellet feedstock (10-‐15 hrs.)

4.) Manufacture new components of extruder head

• Print any parts necessary that are not temperature sensitive and were not previously manufactured from 1st iteration (printing time: 5-‐10hrs)

• Machine any components that are temperature dependent, either in-‐house or professionally, depending on complexity of geometry (5-‐20 hrs.) ( up to three weeks of lead time for professional manufacturing)

5.) Assemble and test • Test extruder head and parts printed based on current testing methods used by Kevin Hedin and Kent Warlick and previously found in research (15-‐20 hrs.)


• Based on testing, modify or redesign components of extruder head to increase composite print quality used in 1st and 2nd iteration of extruder head (5-‐20 hrs.)


Design Evaluation Our main design objective is to produce a high quality composite so there must

be a way to test for quality. Extrusion temperature, feed rate, and nozzle diameter are crucial test variables that need structured experiments to determine optimum printing conditions. Consolidation will be measured with density measurements and fiber volume fraction will be measured with a resin burnout method. Resin burnout involves weighing the produced part and then baking it and letting the resin evaporate so only fibers are left. Those fibers can then be weighed with respect to the original weight to find the percentage of fiber in the material.

Other engineering analysis tools that will be required for a successful product involve mathematical consideration and control systems. Mathematical heat transfer calculations will be required to determine the optimal temperature to extrude the matrix at to ensure proper wetting out of fibers and solidification upon contact with the print plate or previous layers. Die swell will be an important variable to take into consideration when designing and testing. Die swell is determined from the diameter of the extrudate and the diameter of the extrusion nozzle.

Material selection software such as Cambridge Engineering Selector will be a valuable asset for any engineering decisions needing to be made regarding material selection, this is most likely to occur in nozzle design. Control systems will be implemented in regards to extruder head temperature. Controls should be user defined and consistent in nature and therefore a system of heat detection is necessary.

Management Plan

Meeting times

Team Extruder meets Tuesday and Thursday afternoons starting around 1:30pm (depending on when senior design lecture get out). On Tuesday afternoons Team 3D Contour and Team Extruder Head meet in order to coordinate between the two projects. Team Cascade joins this collaborative meeting the first Tuesday of every month to update everyone on current progress and to prepare the interfacing of the three projects. Cascade’s involvement in the collaborative meetings will increase as the design process progresses, and the time comes to start interfacing the projects. After the multi-‐team meetings are finished Team Extruder continues working on the composite extruder head specifically. On Thursday the team initially meets with Dr. Radford, along with the other Boeing composite teams for a short period. Afterwards Team Extruder has its own meeting to prepare questions and concerns, while the 3D contour team meets with Dr. Radford. After meeting with the team’s advisor there is another short team meeting to discuss what was just covered and what needs to be done for the next week, including goals and specific tasks for each team member.


Every Wednesday night before our team meeting with Dr. Radford everyone in the team completes an individual progress report which details what they accomplished in the last week and what they hope to accomplish in the upcoming week. The project manager also completes a progress report for the entire team that is sent to Dr. Radford. The team progress report also includes questions and concerns that the entire team would like to discuss and any additional documentation that is separate from the report. These progress reports are sent to Dr. Radford no later than 8:00 AM the day of the meeting and are stored in a folder on the team’s drive for reference. Every other week the team also gives a PowerPoint presentation to Dr. Radford covering much of the same information. Other meetings times are scheduled as needed to complete certain tasks.

Table 6 -‐ Team Meeting Times

Tuesday Wednesday Thursday Other Days

1:30pm -‐ Combined meeting with 3D Contour Team and Boeing Cascade Basket team(Cascade-‐First Tuesday of the month) -‐ Separate team meeting afterwards

Individual and team progress reports finished and sent by the end of the day Bi-‐weekly progress report finished and sent every other week

2:00pm -‐ Combined advisor meeting 2:15pm -‐ Team meeting time 3:15pm -‐ Meeting with Dr. Radford 3:45pm -‐ Quick team recap

Meetings as necessary to complete tasks


Timeline and Milestones

The main team schedule is set in a Gantt chart built in Microsoft Project. Important milestones which are closer to the present have more exact dates assigned to them. In order to complete three prototypes within the allowed time for this project milestones are set very close together and sometimes overlap. Some important milestones are:

● Oct. 6th: Turn in project plan document

● Week of Nov. 9th: Complete concept generation and evaluation for fiber-‐filament and fiber-‐pellet extruder heads

● Week of Nov. 16th: Complete testing and evaluation of commingled tow

extruder head

● Dec. 3rd: Critical decision meeting to determine focus on commingled tow or fiber-‐filament extruder head development

● Week of Dec. 14th: Complete full 3D CAD and 2D drawings for fiber-‐filament and

fiber-‐pellet extruder heads, begin fiber-‐filament extruder head manufacturing

● Week of Jan. 18th: Finish fiber-‐filament extruder head manufacturing

● Week of Jan. 25th: Finish fiber-‐filament extruder head assembly and begin testing, begin fiber-‐pellet extruder head manufacturing

● Late Feb.: Critical decision meeting to determine focus on fiber-‐filament or fiber-‐

pellet extruder head development, finish fiber-‐pellet extruder head assembly

● Mid Apr.: E-‐Days, finish extruder head project and present, begin integration with other Boeing Composite teams to print composite cascade basket

● Early May: Finish integration with other Boeing Composite teams and attempt

full composite cascade basket print


Concluding Statement

This project plan was intended to communicate what the Composites Extruder Head Development Team will be working on for the academic year. Three iterative design processes will be used to develop the capability to print with three different forms of feedstock material. Difficulties of the development lie in achieving wetting between fibers and matrix as well as between layers and the previously produced layer. Evaluation of the successes put forth by the team most notably involve producing a composite material of high quality.

Budget Breakdown

Table 7 -‐ Team Budget Allotment Item Description Estimated Cost 3D printer A commercially available 3D printer which can

fit our extruder head. Will be used to print test articles for all three prototypes. Split with Contour Team

$600 ($1200 split evenly with contour team, printer may be donated/discounted)

Pico B3 hot end

Commercially available hot end for extruder which will allow printing of commingled tow

$150 (includes shipping, base plate cost)

Glass fiber and PP commingled tow

Commingled glass fiber inside PP matrix to be used for first prototype

$0 (provided by advisor)

Glass fiber E-‐glass fibers used as reinforcing material in second and third prototypes

$40 (6 kg of fiber)

PP filament PP matrix in filament stock form, for use in prototype two

$80 (2 kg of filament)

PP pellet stock

PP matrix in pellet stock form for use in prototype three

$45 (10 lbs of pellets)

Production of custom hot ends

Professional machining for prototype two and three hot ends

$600 ($60 per hour)

I2P printer lab printing

Printing of dual extruder head and prototype parts for all three prototypes

In total the Team was allocated 2,000 dollars to complete all three prototypes. This money was granted through our advisor, Dr. Radford, for use on this project.


References [1] al., F. N. (2015). Additive Manufacturing Of Carbon Fiber Reinforced thermoplastic

Composites using Fused Deposition Modeling. Composites: Part B, Engineering, 80, 369-‐378.

[2] Campbell, F. (2010). Structural Composite Materials. ASM International.

[3] MarkForged Develops 3D Printer For Carbon Fibre. (2015). Reinforced Plastics, 1(59).

[4] Michaeli, W. (2004). Processing Polyethelylene Terephthalate on a Single Screw Extruder Without Predrying Usin Hopper and Melt Degassing. ANTEC, 296-‐298.

[5] Premix Inc., 'Why Composites?', (2015). Available: http://www.premix.com/why-‐composites/adv-‐composites.php. [Accessed: 03-‐ Oct-‐ 2015].

[6] TWI, 'FAQ: How are composites manufactured?', (2015). Available: http://www.twi-‐global.com/technical-‐knowledge/faqs/process-‐faqs/faq-‐how-‐are-‐composites-‐manufactured/. [Accessed: 02-‐ Oct-‐ 2015].

[7] Eichenhofer, Maldonado, Florian, Ermanni, M. (2015). ANALYSIS OF PROCESSING CONDITIONS FOR A NOVEL 3D-‐COMPOSITE PRODUCTION TECHNIQUE. 20th International Conference on Composite Materials, 20th.

[8] Budinski, K. (1979). Engineering Materials: Properties and Selection (9th ed., Vol. 1, p. 773). Upper Saddle River, New Jersey: Reston Pub.

[9]"TWINTEX® PP Mechanical Properties (non Standard)." Fiberglass Industries, Inc. Fiber Glass Industries, Inc, 2013. Web. 5 Oct. 2015. <http://fiberglassindustries.com/twintextechdata.htm>.

[10] Gibson, I., Rosen, D., & Stucker, B. (2010). Additive manufacturing technologies rapid prototyping to direct digital manufacturing (2nd ed., Vol. 1, p. 487). New York: Springer New York. [11] Composite Materials Development. (n.d.). Retrieved October 6, 2015.

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