Overmolding for Vacuum Casting Prototypes

Polyurethane vacuum casting is a great way to make quick-turnaround rapid prototypes. Solid master patterns are used to cast soft silicone rubber molds, and these molds yield up to twenty copies of the original with excellent surface finishes and only a minimal investment in raw materials.

There is also another advantage to vacuum casting prototypes that many people don’t know about. We’re one of the few companies that also offer overmolding on vacuum cast parts, which means combining two or more different resins, in separate steps, to make a single finished piece. Here’s how it works and why it may be another great option for your product development needs.

What is the Purpose of Overmolding?
Overmolding creates finished products that have multiple textures, hardnesses and mechanical properties integrated into a single unified part.
This is not uncommon for production runs of plastic injection molded parts, for example to make soft textured grips on power tool handles. But few people know that it can also be done with polyurethane vacuum casting if you use the right method.

Casting Copies
Once you have these two patterns, silicone molds are cast around each in the normal way. The silicone is poured, allowed to cure, and then the molds opened and the patterns removed, yielding two empty cavities.
The smaller of the two molds, the partial one, is used to cast a copy part. Since this part will form the foundation of the build it must therefore be cast from the harder, more rigid resin material. In this example, the hard plastic enclosure will be overmolded with a soft, textured keypad and bezel surrounding the central display monitor.
After curing, again the mold is opened and the smaller, partially-completed cast copy is removed. This copy is placed into the cavity of the larger, full-sized mold.
Because the cavity in the second mold is larger, when the partially-completed copy is put inside this mold there will be a slight gap between it and the walls of the cavity. This gap represents the area to be overmolded.

Making Patterns
Ordinary vacuum casting requires one master pattern for each molded part. Overmolding requires at least two separate patterns and two separate molds that differ slightly from one another.
The first pattern will be a replica of what the finished part should look like.
The second pattern will be similar, minus the area to be overmolded.
Creating these two patterns is greatly simplified with modern CAD software, which makes it simple to digitally erase sections of the 3D model where you want the overmold to be. These revised models can easily be sent to a 3D printer to create the partial patterns.

Overmolding
In the larger mold we make “feed lines” that lead to the overmolding area, the bezel and the keypad. After the part is placed in the mold, the mold is sealed and the secondary resin, the softer elastomer, is poured into the cavity to fill the feed lines.
This mold is put into the vacuum chamber and heated until fully cured. This creates a permanent bond between the two materials.This process can in theory be done with an indefinite number of overmolding resins. In practice we recommend no more than two resins to avoid complexity and to limit the re-use of the soft silicone molds.
This is just another way we try to offer the best rapid prototyping service in the business. If you think vacuum casting might be right for your next project, upload your CAD drawings for a free quotation today.

IPL 2023: ‘Tough pill to swallow’, says AB de Villiers on RCB’s loss to GT

Former Royal Challengers Bangalore star AB de Villiers said the side’s loss to Gujarat Titans by six wickets at the Chinnaswamy Stadium in Bengaluru on Sunday is a “tough pill to swallow”. The loss meant that the hosts could not qualify for the playoffs in the ongoing Indian Premier League 2023 season.

De Villiers on his Twitter wrote, “Tough pill to swallow. Well tried RCB. Shubman Gill and the Titans simply too good today.” The 39-year-old also appreciated the ton of Virat Kohli as he further wrote “Virat is there when we need him!”

Despite the ton from Kohli RCB could not get over the line as Shubman Gill slammed a sparkling century. The result paved the way for Mumbai Indians’ entry into the playoffs as the fourth team. Kohli scored his seventh IPL century.

However, GT dashed RCB’s hopes by reaching the target in 19.1 overs. For GT, the in-form remained unbeaten on a 52-ball 104, while Vijay Shankar made 53 in 35 in the rain-delayed match.

Asked to bat first, RCB were off to a brisk start with both Faf du Plessis and Virat Kohli finding the boundaries at will. This was Kohli’s second straight hundred.

“I can’t ask anything better from the boys. Last year, everything went well for us. We were expecting people to challenge us. The boys showed tremendous character.” Du Plessis couldn’t hide his disappointment after the defeat.

Also Read
How tweaks on bat-swing from Gary Kirsten, a chilled-out mindset, and sta…
Do we want him to play all his life? Kapil Dev says MS Dhoni has done eno…
How extensive scouting and diligent scouts have made Mumbai Indians the s…
For CSK, MS Dhoni is a habit, he isn't retiring any time soon

“Virat played an unbelievable knock to give us a chance and thought that was a good score, but Shubman played incredibly well to take the game away from us.” Dinesh Karthik’s woeful run with bat really hampered RCB’s prospects this season and on that, Du Plessis said, “Last year DK had a purple patch and was finishing games left, right and centre, but this season it wasn’t to be.

With Rafael Nadal absent, McEnroe tips ‘electric’ Carlos Alcaraz for French Open success

Rafa Nadal’s absence from the French Open due to injury has blown the men’s draw wide open with Carlos Alcaraz the “slight favourite” over Novak Djokovic, former Grand Slam champion John McEnroe has said.

Nadal has not played since his hip injury at the Australian Open and the 14-times winner at Roland Garros said it could be months before he returns to action as he prepares to end his career in 2024.

“Honestly it was just so one-sided the way Rafa was able to dominate that all you can talk about is Rafa,” McEnroe told Eurosport.

“Novak has as many Grand Slams (22), but you don’t put him in the same breath there (at Roland Garros) as Rafa. He set a bar so high that it’s impossible to imagine anyone even get close to it.

“So from that standpoint alone, it’s much more open … The ideal would have been, if Rafa was still playing at a very high level and someone was good enough to beat him when he’s playing great. That’s what people really wanted to see.”

McEnroe said Djokovic has a great chance to win a calendar slam this year but the 64-year-old said youngsters like world number one Alcaraz and Holger Rune can make the step up.

“I would say Alcaraz would be the slight favourite to win this,” McEnroe said.

Advertisement

“Alcaraz has a lot of pressure now because he’s just such an unbelievable breath of fresh air. He’s so electric, the way he plays, he’s got such a great personality that people want him to win.

Also Read
French Open: Doubles pair disqualified after ball girl is hit
Records are good but now it's about the next step says Novak Djokovic
French Open 2023: Coco Gauff and Iga Swiatek can set up a rematch of last…
Rafael Nadal posts update after surgery, says normal recovery process is …

“But then you got to back it up. He’s 20-years-old, but he just seems like such a great ambassador for our sport that you’re sort of pulling for him.”

Click Here: canberra raiders team jersey