History of AM Making of layered items of commercial importance has a history that goes back thousands of years. For example, single sheets of paper were made by forming (via filtration on a screen) and drying a layer of fiber made from pulp. Since the beginning of industrial revolution, multiply boxboard has been made by making continuous individual layers of fiber, with each layer being combined with the subsequent layer in continuous box-board making machines. AM processes are different because they employ a variety of materials and unlike the manufacture of paper and paperboard, there are no restrictions on the geometry, shape and internal structure of the part. The location, shape, thickness and internal structure of each layer is always under positive control of the AM system. We explore the history of AM, beginning with two precursor technologies that form the root of modern AM practice. These precursors were 3-dimensional relief maps from the field of topography and sculpture made from multiple photographs of the object (or subject), taken in the round. This gave rise to techniques of photosculpture. Module 1b - History of AM 1 1

History of Additive Manufacturing –Then From topography and photo sculpture 1860: Willeme (US Patent US43822 A, 1864) Photosculpture method to recreate pictures in 3D 1890: Blanther (US Patent US473901 A) Layered method to create topographical relief maps 1951: Munz (US Patent US2775758 A) Basis of stereolithography techniques introduced 1968: Swainson (US Patent US4041476 A, 1971) 3D polymerization with laser beams 1971: Ciraud (FRG Disclosure Publication 2263777) Powder process proposed The use of photography to make an exact 3-dimensional replica of an object predates the development of 3-dimensional relief maps by nearly 30 years. In 1860 one particularly successful embodiment of this technique was developed by François Willeme, and patent in the US in 1864. In Willeme’s method, the subject was placed in circular room and simultaneously photographed by 24 cameras placed equally about the circumference of the room. An artisan then carved a 1/24th cylindrical portion of the figure using a silhouette of each photograph. Blanther suggested a layered method for making a mold for topographical relief maps. He obtained a US patent in 1890. The method consisted of impressing topographical contour lines on a series of wax plates and cutting these wax plates along the contour lines. After stacking and smoothing these wax sections, Blanther obtained a positive and negative three-dimensional forms with a surface that corresponds to the terrain indicated by the contour lines. A paper map was pressed between the positive and negative forms to create a raised relief map. Munz proposed a system that has features of present day stereolithography techniques. Munz received a US patent in 1951. In 1968, Swainson proposed a process to directly fabricate a plastic pattern by selective, three-dimensional polymerization of photosensitive polymer at the intersection of two laser beams. Swainson received a US patent in 1971. In 1971, Ciraud disclosed a process that has all the features of modern direct deposition AM techniques. His technique fused small particles of material using a laser, electron beam or a plasma beam to heat and melt the particles locally. Consequently, the particles adhere to each other when cooled and solidified. His process was disclosed in an FRG Disclosure. Module 1b - History of AM 2 2

History of Additive Manufacturing 1972: Matsubara (Mitsubishi Motors) Photo-hardening materials 1979: Nakagawa (Tokyo University) Laminating techniques to create functional tools 1979: Householder (US Patent US4247508 A) Earliest description of powder laser sintering – never commercialized 1986: Hull (US Patent 4,575,330) Coined the term Stereolithography 1989 Deckard (US Patent US4863538 A) First commercial use of Selective Laser Sintering (a DARPA project) 1980's – today: Advancements in processes, CAD, file storage/structure, materials, technology (machines) and development of Additive Manufacturing community; development of the Maker Movement Matsubara, in 1972, proposed a topographical process that used photo-hardening of materials to create thin sheets of a desired shape from a photopolymer material. These sheets were then stacked together to make a casting mold. In 1979, Nakagawa, used lamination techniques to produce tools, used for blank forming, press forming and injection molding. Also in a 1979 US patent, Householder presented the earliest description of a powder laser sintering process. He revealed sequentially depositing planar layers and solidifying a portion of each layer selectively. This method was never commercialized. In 1986, Hull revealed a method for creation of 3-D object, in layers, by using Stereo-lithography. Hull described stereolithography as a method for making solid objects by successively “printing” thin layers of a curable material. A programmed moving beam of UV light is directed on the thin layer, selectively hardening areas of the layer to create a hardened slice of the object’s cross-section. By repeated layering and hardening of successive cross- sections, the entire object can be created. In a 1989 patent, Deckard revealed a system for producing part by selective sintering of powder layers, using a scanning laser. The powder can be made of plastic, metal, ceramic or a polymer. Deckard demonstrated the first commercial use of Selective Laser Sintering. In the 1980s and continuing, AM processes saw major developments in software, storage, materials, machine systems and the growth of AM Community and the Maker Movement. Module 1b - History of AM 3 3

Additive Manufacturing: Now 1980’s – 2000s Mainly pre-production applications Prototyping Proof of concept Manufacturability and Repeatability demonstration Optimization of the manufacturing process Verification and internal testing External units (> 100) for customer testing In the two decades from 1980 to 2000, AM saw commercial applications in pre-production activities. These include prototyping, demonstrating proof of concept, engineering scale demonstration necessary to build confidence in the industry; production of small batch runs of parts for testing and validation purposes. Module 1b - History of AM 4 4