{"id":29281,"date":"2023-09-03T13:16:58","date_gmt":"2023-09-03T20:16:58","guid":{"rendered":"https:\/\/www.podfeet.com\/blog\/?p=29281"},"modified":"2023-09-15T11:36:33","modified_gmt":"2023-09-15T18:36:33","slug":"titanium-iphone","status":"publish","type":"post","link":"https:\/\/www.podfeet.com\/blog\/2023\/09\/titanium-iphone\/","title":{"rendered":"Why Might Apple Create a Titanium iPhone?"},"content":{"rendered":"<figure style=\"float: right; margin-left: 10px\"><img decoding=\"async\" src=\"https:\/\/www.podfeet.com\/blog\/wp-content\/uploads\/2023\/09\/Marks-Standard-Handbook-for-Mechanical-Engineers.jpg\" alt=\"Marks Standard Handbook for Mechanical Engineers\"  title=\"Marks' Standard Handbook for Mechanical Engineers.jpg\" width=\"300 \" height=\"\"><figcaption style=\"text-align:center\">Marks&#8217; Handbook from My Dad in 1978<\/figcaption><\/figure>\n<p>It\u2019s the time of year when the wild and unsubstantiated rumors about the new iPhone and Apple Watch are resolving into less wild and more substantiated rumors. In less than two weeks we\u2019ll know what\u2019s coming but the frenzy doesn\u2019t slow down just because we\u2019ll know soon.<\/p>\n<p>One of the rumors is that Apple is going to eschew the stainless steel rim around the iPhone in favor of titanium.  The Apple Watch Ultra comes in titanium but they don\u2019t tell us <em>which<\/em> titanium. They only call it \u201caerospace-grade titanium.\u201d<\/p>\n<p>As a mechanical engineer in my day job for many years, I had the opportunity to choose materials to build things, so I know a little bit about why you\u2019d make the tradeoff between steel, aluminum, and titanium.  And better yet, I feel the need to share a bit of what I know.<\/p>\n<p>Metals have a few properties to consider. In military devices like what I worked on that often went on aircraft, and in commercial electronics like iPhones, a big consideration is trying to make the devices lighter without sacrificing strength.<\/p>\n<p>Weight is a function of how dense a material is, which is mass divided by volume. In metric units, we use grams per cubic centimeter.  So let\u2019s take a look at three materials and see which one we should use to make our proposed iPhone, based entirely on density so it won\u2019t weigh down our purses so much.<\/p>\n<p>We\u2019ll compare three metals:<\/p>\n<ul>\n<li><strong><a href=\"https:\/\/asm.matweb.com\/search\/SpecificMaterial.asp?bassnum=ma6061t6\">Aluminum alloy<\/a><\/strong> which is a blend of aluminum with a dash of magnesium and silicon. For the nerdy amongst you, I\u2019ll be using 6061-T6 specifically, but don\u2019t worry your pretty little head about that if you\u2019re not into materials specifications. I like this one because I actually remember specifying 6061 on my drawings back in the early 1980s.<\/li>\n<li><strong><a href=\"https:\/\/asm.matweb.com\/search\/SpecificMaterial.asp?bassnum=NL3011\">Stainless Steel<\/a><\/strong> \u2014 in this case, I\u2019ll be using 301 for the properties.<\/li>\n<li><strong><a href=\"https:\/\/asm.matweb.com\/search\/SpecificMaterial.asp?bassnum=mtp641\">Titanium Ti-6Al-4V<\/a><\/strong> where the &#8220;Al&#8221; and &#8220;V&#8221; stand for Aluminum and Vanadium to make the alloy. Apple simply says \u201caerospace-grade titanium\u201d, and the ASM folks say it&#8217;s good for &#8220;Blades, discs, rings, airframes, fasteners, components. Vessels, cases, hubs, forging, and biomedical implants.&#8221; <\/li>\n<\/ul>\n<p>My main source of data for this exercise is from <a href=\"https:\/\/www.aerospacemetals.com\/contact-aerospace-metals.html\">asm.matweb.com<\/a>. ASM stands for the American Society for Materials, and I bet their conferences are a hootin\u2019 good time.<\/p>\n<p>I\u2019d also like to point out that I cross-referenced as much as I could from the book my father gave me shortly after I graduated from college. The book he gave me (when my mother wanted to give me a dress (can you imagine?)) is <a href=\"https:\/\/www.amazon.com\/Marks-Standard-Handbook-Mechanical-Engineers\/dp\/0071428674\" target=\"_blank\" rel=\"noopener\">Marks&#8217; Standard Handbook for Engineers<\/a>, 8th edition published in 1978. The specific table I used for cross-referencing the materials information is on page 6-11. I wasn&#8217;t able to cross-reference as much as I&#8217;d hoped as materials have advanced since 1978!<\/p>\n<figure style=\"float: center; margin: 10px\"><img decoding=\"async\" src=\"https:\/\/www.podfeet.com\/blog\/wp-content\/uploads\/2023\/09\/Titanium-highlighted-in-Marks-Handbook.png\" alt=\"Titanium highlighted in Marks Handbook\"  title=\"Titanium highlighted in Marks Handbook.png\" width=\"600 \" height=\"307\"><figcaption style=\"text-align:center\">Aluminum 6061 from Marks&#8217; Handbook<\/figcaption><\/figure>\n<p>Okay, with my sources duly referenced, let\u2019s get into the good stuff.<\/p>\n<p>If we look at the density alone of the three materials we\u2019ve chosen, we find that the aluminum alloy has the lowest density at 2.7 grams per cubic centimeter.  Steel comes in at over 8, and titanium comes in at 4.4.<\/p>\n<p>Clearly, we should use aluminum for our fantasy iPhone because it has the lowest density, right?  Slow down, Skippy, there\u2019s more to the story than just the density.  What if Aluminum isn\u2019t as strong as the other contenders for the same volume? Don\u2019t you want your iPhone\u2019s frame to be strong?<\/p>\n<p>One measure of strength is Ultimate Tensile Strength.  Sounds like something one of those shows with people fighting for physical supremacy should use, doesn\u2019t it? Strength is measured in Freedom Units in psi or pounds per square inch, but in the rest of the world, it\u2019s measured in megapascals. A Pascal is one Newton per meter squared, and a Newton is one kilogram-meter per second squared. I bet <em>that&#8217;s<\/em> more than you wanted to know, isn&#8217;t it? Sorry, couldn&#8217;t help myself. Let&#8217;s get back to the plot at hand.<\/p>\n<p>How do our three materials measure up in the Ultimate Tensile Strength contest?<\/p>\n<p>Our previous fan-favorite, aluminum, comes in at a paltry 310 megapascals, while stainless steel comes in at a strong 862 megapascals. Don\u2019t count titanium out yet though, it finishes with a winning 950 megapascals. It\u2019s more than triple the Ultimate Tensile Strength of aluminum!<\/p>\n<p>Now we have a quandary. While aluminum has the lowest density, titanium is the clear winner when it comes to Ultimate Tensile Strength. How do we decide?<\/p>\n<p>The answer is to calculate the Specific Strength.  You\u2019re going to absolutely love this one. The unit for Specific Strength is kilonewton-meter per kilogram.  I am not making this up.  While the units are clearly getting out of control, calculating Specific Strength is trivial. We simply divide our old friend Ultimate Tensile Strength by density.<\/p>\n<p>Our three contestants, aluminum, steel, and titanium come in with these final stats for Specific Strength:<\/p>\n<ul>\n<li>Stainless Steel at 107 kN-m\/kg<\/li>\n<li>Aluminum alloy 6061-T6 comes in second at 115 kN-m\/kg<\/li>\n<li>Titanium wins the battle for the materials at over 214 kN-m\/kg<\/li>\n<\/ul>\n<p>Now that we know titanium is the clear winner in the materials battle, what does this really mean?<\/p>\n<p>If Apple chose Titanium for the next iPhone, they could keep the exact same frame design and swap out the heavy, but relatively strong, stainless steel for titanium. Since titanium is less dense, the same-sized frame would be much stronger.<\/p>\n<p>Alternatively, they could choose to make the frame thinner, while maintaining the same strength.<\/p>\n<p>The last thing to take into consideration is cost. Titanium is a lot more expensive than stainless steel for a couple of different reasons.<\/p>\n<p>Titanium is rarer than the elements required to make stainless steel, so the material costs alone would make the phone more expensive. Titanium is also much harder to machine. Machining the same iPhone frame out of titanium would increase the cost of making the device. We&#8217;ve heard rumors of an increase in the base price, and this could be one of the reasons why.<\/p>\n<p>I don\u2019t know what Apple will do with the next iPhone but I hope you enjoyed my little lesson on why titanium might be in our future for more than the Apple Watch Ultra.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Marks&#8217; Handbook from My Dad in 1978 It\u2019s the time of year when the wild and unsubstantiated rumors about the new iPhone and Apple Watch are resolving into less wild and more substantiated rumors. In less than two weeks we\u2019ll know what\u2019s coming but the frenzy doesn\u2019t slow down just because we\u2019ll know soon. One [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":29283,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[147],"tags":[6050,374,70,6051,5568,6049,5738],"class_list":["post-29281","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog-posts","tag-aluminium","tag-aluminum","tag-iphone","tag-iphone-15","tag-stainless-steel","tag-steel","tag-titanium"],"jetpack_featured_media_url":"https:\/\/www.podfeet.com\/blog\/wp-content\/uploads\/2023\/09\/Titanium-crystal_bar-1040x520-1.jpeg","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.podfeet.com\/blog\/wp-json\/wp\/v2\/posts\/29281","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.podfeet.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.podfeet.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.podfeet.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.podfeet.com\/blog\/wp-json\/wp\/v2\/comments?post=29281"}],"version-history":[{"count":7,"href":"https:\/\/www.podfeet.com\/blog\/wp-json\/wp\/v2\/posts\/29281\/revisions"}],"predecessor-version":[{"id":29377,"href":"https:\/\/www.podfeet.com\/blog\/wp-json\/wp\/v2\/posts\/29281\/revisions\/29377"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.podfeet.com\/blog\/wp-json\/wp\/v2\/media\/29283"}],"wp:attachment":[{"href":"https:\/\/www.podfeet.com\/blog\/wp-json\/wp\/v2\/media?parent=29281"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.podfeet.com\/blog\/wp-json\/wp\/v2\/categories?post=29281"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.podfeet.com\/blog\/wp-json\/wp\/v2\/tags?post=29281"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}