An Affordable, Production Ready Carbon Fiber Process is Here

John Moore — Thu, 09 Oct 2014 20:53:11 +0000

Weight to strength ratio along with its aesthetic appearance has always made carbon fiber an attractive material choice. However due to it’s excessive startup costs and molding complexities it has been out of reach for many. Molding carbon fiber reinforced composites (CFRP) has mostly been dedicated to the aerospace industry along with other low volume niche` applications. In recent years the automotive sector has joined in on molding CFRP with high-end steel tooling. While high-end steel tooling may prove to be an effective cost model for high volume applications, majority of the vehicles or applications that benefit from the advantages of carbon fiber are currently low volume niche` applications.

Molding CFRP is not new, however due to the lack of innovation it’s still dedicated for being used for low to moderate volume production. Typical methods being either prepreg with very high material and tooling cost — with at best 1 cycle per day in production – or vacuum infusion with similar production speeds but only one smooth finished side.

Requested Solution

We were challenged to create a package that provided low cost entry to CFRP molded class “A” surface panels. The solution had to include low cost tooling, the ability to run in extended daily production, minimum of 1 part per 2 hours, and ultimately meet speeds of 15 minutes or less. All while maintaining a surface quality as though it was molded in match metal tooling on both the “A” and “B” sides of the part.

Solution Provided

Leveraging our 30+ years of experience and using tooling design from the LRTM process in combination with elements from HP-RTM, we developed a packaged solution — far exceeding expectations —, which was used to produce the door skin example shown here. Included in the package was cost effective tooling and equipment, along with complete process training.

The example tool shown here is first part off of the mold without any process refinement! The door skin is shown with “as molded” carbon fiber “A” surface, primer, and finally top coated sections. It should be noted that there is no coating applied to the carbon fiber in the mold. The part contains 1448 grams of Momentive epoxy 035/038 resin system and 1730 grams of carbon fiber. Resulting in fiber volume fractions of 48% and a nominal part thickness of 2mm. Total weight of the door skin is 7 pounds, which far lighter than any comparable steel door outer — averaging 14.38 pounds.

Using the developed package along with the included Infuser Servo® injection system, a precise automated injection of 1448 grams of resin was injected into the mold in less than 90 seconds. The tooling used to create the example part is a “soft” FRP mold set (LRTM) with replaceable “A” cavity side mold surface, allowing for the “A” mold to be replaced at an affordable cost of $710. Complete startup cost for tooling came to $16,729.

As Molded “A” Side

As Molded “B” Side

This part and more will be at our booth #3648 during CAMX 2014 in Orlando, Florida!

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Today…You Can Create Your Mold as Easy as Making a Part!

John Moore — Thu, 24 Jul 2014 16:03:48 +0000

In the late 90′s there were two innovative tooling methods to address the shortcomings of “soft” FRP Tooling as used for the “RTM” molding process at that time. These were the VEC and MIT technologies. VEC brought rapid and even temperature control using a tank of water as the mold base. The VEC tool was also far less structure as compared to the typical RTM tools of that time due to the support the tank of water provided, thus reducing the cost of the VEC mold since the tanks were common to several mold shapes.

Mold Insert Skin Tooling (MIT)

The MIT process method offered a “Mold Insert Skin” that allowed the mold cavity half to be “resurfaced” instantly. Soon however, it was clear that having extra MIT skins would allow for process steps such as Gel Coating, Fiber Loading and De-Molding to be done simultaneously while another part was in the actual mold set being injected and curing. The results proved that a MIT mold set could then increase productivity by as much as 270% by having as many as five mold skins rotating in the tool set. It should be said, that the construction of a FRP mold is made of tooling gel coat and fiber reinforced tooling resin, yet historically these materials were permanent as the mold surface by the mold building process attaching the mold base structure directly to the said mold surface mold laminate. MIT simply separates the mold surface laminate from the mold structure in a precise manner. This method has been used on a variety of parts ranging in size from a Baseball Cap to a 21′ Boat Hulls and Decks. Today, this innovative tooling design has been given some new enhancements, in the past the lower half (bolster) of the production tool set was needed to make new skins So production was lost while the lower mold half was making new MIT skins. Now, using a combination of the OSM Glass Master used to make the cavity and an LRTM upper mold matched to the Glass Master we make the MIT Skins using the LRTM process. This new molded MIT skin then fits perfectly and is vacuum locked into the production mold lower “bolster” to create a lower mold half. Today we have in effect enabled the LRTM process to make new tool surfaces, as easy as, making a part at a comparable cost. Naturally the MIT Skin is made with Tooling Gel Coat and Tooling Resin with fiber reinforcement, yet cost is far more comparable to a part then making whole mold set. Having the ability to simply mold a new mold skin completely off line at a very nominal cost is proving to completely change the economics of FRP soft tooling allowing for dramatic reduction in post mold finishing as was historically common as the life of the mold developed surface imperfections that were transferred to each subsequent molding produced. What we find what makes this possible is the precise injection control provided by the JHM Technologies Infuser PRG injection system. While this same process control has proven useful in reducing cost in making of production parts, it is now proving to allow the cost of tooling and tool replacement to be far more attractive as well.

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