The practice of forging has evolved over the ages and what began as an art form, where decorative objects were produced from precious metals, developed into a technically advanced manufacturing process, with an equally complex supply chain.
Forging is now a major global industry, supplying components for many of the world’s most innovative products and industries: automotive, truck & bus, defense, aerospace, and energy, which makes it imperative for supply chain professionals sourcing forged components to understand the process types, value stream map, technical advantages, and early supply partner involvement to effectively execute strategic procurement.
Forging is the application of thermal and mechanical energy to steel billets or ingots to cause the material to change shape while in a solid state. There are a variety of different forging types, Open Die Forging and Ring Forging to name a few, but the most common process is referred to as Closed Die Forging. This is the shaping of hot metal completely within the walls or cavities of two dies, that come together to enclose the work piece on all sides. The impression for the forged design can be entirely in either die, or split between the top and bottom dies.
Value Stream Map
To gain a better understanding of the process flow, let’s break it down into steps. Before the forging process can even take place, the forging company must source the raw material from either a steel mill or a qualified steel service center. Once this relationship is built, the forging company will begin receiving shipments of raw steel bar stock that should ultimately meet the quality specifications required by the end customer, which is usually confirmed in the APQP process. The bar stock is then cut or stamped to the appropriate length, based on the part requirements, and transported to the processing area.
Now that the material is in billet or ingot form, it is heated through a furnace and placed on the bottom half of the die either manually by an operator or by an automated process. Next, the forging press stamps the billet into the form of the die. The newly forged part is then removed from the die and placed in a separate storage area for cooling. The majority of finished forged parts leave behind some debris, which requires them to be shot-blasted before they can be packaged and shipped to the customer’s facility.
As many supply chain professionals know, the forging process is not a recent innovation in the manufacturing sector; it has been around for many years. On the other hand, it is critical to understand how and why certain components are best suited for the forging process and how to use this process as a competitive advantage to drive out waste in the supply chain by ensuring the right process is paired with the right part. As opposed to using alternative methods, such as die casting to manufacture the parts required for a final assembly, forging brings a variety of financial benefits, as well as efficiency from a part characteristics perspective:
- Structural Strength: Forging offers structural integrity that is unmatched by other metalworking processes. It eliminates internal voids and gas pockets that can weaken metal parts. This ultimately reduces part inspection requirements and resources, simplifies heat treating and machining, and ensures optimum part performance in conditions that require the part to be weight bearing and durable. In most cases, the forging process is used to produce components that cannot fail and are located in critical areas of performance, such as vehicle engine blocks and transmissions.
- Low Scrap Rates: One of the most value-adding financial benefits of forging is the fact that it leaves behind very little wasted material, or as most people refer to as scrap. During the forging process, the steel billets are simply heated and re-shaped, as opposed to machining, which removes material, or casting, which involves much more processing of raw material.
- Fast Cycle Times: The forging process generally has faster cycle times than its rival production methods. Forging only takes around 5 to 10 seconds per cycle compared to casting or machining where one cycle may potentially take minutes. This allows forging supply partners to maximize output and drive efficiency internally, ultimately leading to low piece price costs.
Early Supply Partner Involvement
We recently met with Joseph Schwegman, President of Quality Steel Products, and discussed at great length the importance of the Supply Chain and Engineering teams working closely and embracing the Design for Manufacturing mentality during the product design phase so that the most feasible manufacturing process is identified early on, thus eliminating re-work in the future. Many supply chain professionals consider forged components to be a simple component group to source and manufacture, but there have been several changes and recent innovations, including the growth of titanium forged parts in the aerospace industry.
Titanium and aluminum materials are becoming more common, especially in the aerospace and medical device industries, due to the increasing need to optimize performance and decrease part weight. As these complex parts become smaller and more lightweight, torque and stress on the parts tends to increase, which poses many design challenges. Even though processes like casting or metal injection molding tend to accommodate parts that contain complex features with tight tolerances more effectively, this scenario is presenting new opportunities for the forging industry that is highly capable of supporting these high-strength requirements.
Supply chain professionals should be well-versed within above key considerations before sourcing a forging to ensure sourcing success. There must be cross-functional team awareness on the true cost and not just the short-term piece price cost to ensure long-term forging supply success. Forgings are unique and every case must be analyzed and clearly understood prior to starting the procurement process. Keep in mind these key considerations and you will be well positioned to offer your company the best supply options while driving down your forging true cost, which will create a win-win value and relationship across organization and supply partners.